Technical writing
FMCSA Motor Carrier Census: The Federal Database Behind 2 Million Registered Trucking Companies
The FMCSA motor carrier census records every entity that holds a USDOT number — roughly 2.18 million interstate trucking companies, bus and motorcoach operators, hazardous materials carriers, freight forwarders, and brokers — the single federal registry that underpins safety oversight, insurance underwriting, and freight broker vetting across the entire US trucking industry.
What the FMCSA census is
The Federal Motor Carrier Safety Administration (FMCSA) is the modal safety agency within the US Department of Transportation responsible for reducing crashes, injuries, and fatalities involving large trucks and buses. It was created by the Motor Carrier Safety Improvement Act of 1999, which split the motor carrier safety mission out of the Federal Highway Administration into a dedicated agency. At the operational core of everything FMCSA does sits a single registry: the motor carrier census, a master file of every entity that has ever been issued a USDOT number. We hold a snapshot of this registry as the tablefmcsa_carriers, covering approximately 2.18 million registered entities.
The census is not a list of trucks. It is a list of regulated entities — legal persons that conduct, or hold themselves out to conduct, an activity within FMCSA's jurisdiction. That population is broader than the word “trucking” suggests. It includes for-hire freight carriers that haul property for compensation; private carriers that move their own goods in their own trucks; passenger carriers operating buses, motorcoaches, and limousines; carriers of hazardous materials in quantities that require placarding; freight forwarders that assemble and disassemble shipments under their own bills of lading; brokers that arrange transportation without taking custody of freight; and intermodal equipment providers that supply chassis for container movement. Each of these entity types is registered in the same census, distinguished by classification flags rather than by separate databases.
The census is the spine that every other FMCSA system hangs from. The agency's roadside inspection records, crash files, enforcement case records, insurance filings, and safety ratings are all keyed to the USDOT number. When a state trooper inspects a truck at a weigh station, the inspection is written against the carrier's USDOT number. When an insurer files proof of coverage, it files against the USDOT number. When a broker vets a carrier before tendering a load, the broker looks up the USDOT number. The census is therefore both a registration roster and the primary key for the entire federal motor carrier safety data ecosystem.
Because registration is a precondition for legal interstate operation, the census is close to a complete enumeration of the regulated industry — subject to two important caveats discussed later: it includes a large stock of defunct carriers whose records were never closed, and it relies on self-reported data that carriers are required, but frequently fail, to keep current.
The USDOT number and operating authority
Two distinct federal registrations govern a motor carrier, and conflating them is the most common error in interpreting the census. The first is the USDOT number; the second is operating authority, identified by an MC number.
The USDOT number is a safety identifier. Any company that operates commercial motor vehicles in interstate commerce transporting passengers, or hauling cargo above the federal weight threshold (a gross vehicle weight rating of 10,001 pounds or more), or transporting placardable quantities of hazardous materials, or carrying enough passengers to require registration, must obtain a USDOT number. The number is the unique identifier FMCSA uses to monitor a company's safety record, inspections, crash involvement, and compliance reviews. Crucially, both for-hire and private carriers need a USDOT number — safety jurisdiction does not depend on whether the carrier hauls for others or only for itself.
Operating authority (the MC number, sometimes called the docket number) is an economic registration. It grants the legal right to operate as a for-hire carrier transporting regulated commodities for compensation, or to operate as a broker or freight forwarder. Where the USDOT number answers “is this entity safe to operate,” the MC number answers “is this entity permitted to engage in for-hire transportation for money.” A private carrier hauling only its own goods needs a USDOT number but no MC number, because it is not in the for-hire business. A broker, conversely, may hold an MC number for brokerage authority while operating no trucks at all. The categories of operating authority include motor carrier of property, motor carrier of passengers, broker of property, broker of passengers, and freight forwarder, and a single entity can hold more than one.
Operating authority also carries financial-responsibility obligations that a bare USDOT registration does not. For-hire carriers must file proof of insurance (the BMC-91 or BMC-91X form) at federally mandated minimums, and brokers and freight forwarders must file a surety bond or trust fund (the BMC-84 or BMC-85) — set at $75,000 for brokers under the MAP-21 reforms. Failure to maintain these filings results in revocation of operating authority while the USDOT number itself may remain active. This is why the census frequently shows entities with an active USDOT number but inactive or revoked operating authority: the safety registration and the economic registration have independent lifecycles.
The MCS-150 and the biennial update requirement
The document that creates and maintains a census record is the MCS-150, the Motor Carrier Identification Report. A company files an MCS-150 to obtain its initial USDOT number, and the form collects the data that becomes the carrier's census record: legal name and any doing-business-as (DBA) name, physical and mailing address, the type of operation (interstate or intrastate, for-hire or private, passenger or property), the cargo classifications the carrier expects to haul, whether the carrier handles hazardous materials, and — most consequentially for analysis — the size of the operation as measured by the number of power units (tractors, straight trucks, and buses) and the number of drivers.
Federal regulation (49 CFR 390.19) requires every carrier to update its MCS-150 at least once every two years, on a schedule keyed to the last two digits of its USDOT number, regardless of whether any information has changed. This is the biennial update requirement. The next-to-last digit determines whether the update is due in an odd or even year, and the last digit determines the month. A carrier that fails to file its biennial update can have its USDOT number deactivated and its operating authority placed at risk, and the failure itself is a recorded compliance event.
The biennial update is the mechanism that is supposed to keep the census fresh, and its imperfect compliance is the single most important data-quality fact about the dataset. Power-unit and driver counts are captured at filing time and only refreshed when the carrier files again. A carrier that grew from five trucks to fifty between filings will show five until its next MCS-150. A carrier that ceased operations entirely but never filed a final update will continue to appear with its last-reported fleet size and an active status until FMCSA deactivates it for a missed biennial cycle. Any analysis of fleet size or operating status from the census is therefore an analysis of last-reported values, not current reality.
Carrier classification
The census classifies each entity along several orthogonal dimensions, and these classification flags are what make the dataset analytically useful for market-structure and risk work. The major axes are the following.
For-hire versus private. A for-hire carrier transports the property or passengers of others for compensation; a private carrier transports its own goods in furtherance of its primary (non-transportation) business. A grocery chain running its own delivery fleet is a private carrier; a contract freight hauler is for-hire. The distinction governs whether operating authority is required and shapes the insurance and economic-regulation regime that applies.
Interstate versus intrastate. Interstate operation crosses state lines, or moves goods or passengers that are part of a continuing interstate journey, or crosses an international boundary. Intrastate operation stays entirely within one state. FMCSA's safety jurisdiction is primarily over interstate commerce; intrastate carriers are regulated mainly by their state, though many states have adopted the federal safety regulations and many intrastate carriers still appear in the census because they handle hazardous materials or operate vehicles that trigger registration. The census records the carrier's self-declared operation classification, which determines which body of regulation controls.
Passenger versus property. Passenger carriers move people — intercity motorcoaches, charter and tour buses, commuter operators, and large-capacity limousine services — and are subject to heightened scrutiny because of the catastrophic potential of a single bus crash. Property carriers move freight. The census flags passenger operation distinctly, and FMCSA maintains a separate consumer-facing tool (SaferBus) precisely because passenger-carrier safety is a distinct public concern.
Hazardous materials. Carriers that transport hazardous materials in quantities requiring placarding, or any quantity of certain highly hazardous materials, carry a hazmat flag and are subject to an additional layer of regulation administered jointly with the Pipeline and Hazardous Materials Safety Administration. Hazmat carriers face a dedicated safety-permit regime for the most dangerous commodities and constitute one of the seven safety-monitoring categories described below.
These flags are not mutually exclusive. A single carrier can be an interstate, for-hire, property carrier that also holds a hazmat endorsement — the classification fields combine to describe the carrier's full regulatory profile, and population analysis of the census typically begins by cross-tabulating these dimensions.
Operating status, fleet size, and commodities
Beyond classification, three field groups carry the most analytical weight in the census: operating status, fleet size, and commodity types.
Operating status records whether the carrier is currently authorized to operate. The principal values are active (authorized and in good standing), out-of-service (subject to a federal order prohibiting operation, typically following an unsatisfactory safety rating or an imminent-hazard determination), inactive (the USDOT number has been deactivated, often for a missed biennial update or a voluntary cessation), and revoked (operating authority has been withdrawn, commonly for lapsed insurance or unpaid penalties). An out-of-service order is FMCSA's most serious administrative sanction short of criminal referral: a carrier placed out-of-service may not operate any commercial motor vehicle, and continuing to operate is a serious violation. The distinction between a deactivated USDOT number and revoked operating authority matters because, as noted, the two registrations can be in different states simultaneously.
Fleet size is captured as two self-reported counts: power units and drivers. Power units are the motorized vehicles — tractors, straight trucks, and buses — that the carrier operates. Drivers is the count of employed and contracted drivers. These two numbers, despite their staleness, are the principal lens on industry structure. The US trucking industry is famously bimodal: a small number of very large fleets operate tens of thousands of power units, while the overwhelming majority of carriers are tiny. A large fraction of all registered for-hire carriers report a single power unit — the owner-operators who own and drive one truck. Roughly the great bulk of carriers operate six or fewer power units. This long-tail structure is why the industry is so difficult to regulate uniformly and why freight brokers must vet each small carrier individually: there is no concentrated set of large counterparties to monitor.
Commodity types record the cargo classifications the carrier expects to haul, drawn from a standard FMCSA list — general freight, household goods, metal, motor vehicles, machinery, building materials, agricultural and farm supplies, refrigerated food, beverages, chemicals, petroleum, livestock, and many others, including the hazardous-materials sub-classifications. These are self-declared expectations rather than verified operations, so they describe what the carrier registered to do, not necessarily what it actually hauls. Still, commodity flags are useful for segmenting the census — isolating refrigerated carriers, or tanker operators, or household-goods movers (the segment with its own consumer-protection regime because of moving-fraud concerns).
Safety oversight: CSA and the seven BASICs
The census is the registration layer; safety oversight is what FMCSA does on top of it. The agency's flagship safety-monitoring program is CSA — Compliance, Safety, Accountability — launched in 2010 to replace an older rating system. CSA is built to identify high-risk carriers early, using the continuous stream of roadside-inspection and crash data rather than waiting for an infrequent on-site compliance review. Its analytical engine is the Safety Measurement System (SMS), which scores every carrier with sufficient inspection data and ranks it against peers.
SMS organizes carrier performance into seven categories called BASICs — Behavior Analysis and Safety Improvement Categories. Each BASIC aggregates the violations and events that fall within a particular safety behavior, weights them by severity and by how recently they occurred, normalizes the result against the carrier's exposure (typically inspections or vehicle-miles), and produces a percentile ranking relative to a peer group of carriers with a similar number of inspections. The seven BASICs are:
- Unsafe Driving — dangerous or careless operation of a commercial motor vehicle: speeding, reckless driving, improper lane changes, inattention, and failure to use seat belts, drawn from moving-violation citations and inspection findings.
- Hours-of-Service (HOS) Compliance — operation of a vehicle by a fatigued driver, measured through hours-of-service violations, including logbook and electronic-logging-device falsification and exceeding driving-time limits. This BASIC was previously labeled Fatigued Driving.
- Driver Fitness — operation by a driver who is unfit by reason of training, experience, or medical qualification: missing or invalid commercial driver's licenses, lapsed medical certificates, and disqualified drivers.
- Controlled Substances / Alcohol — operation under the influence of, or impaired by, alcohol or controlled substances, including drug- and alcohol-testing-program violations and possession findings.
- Vehicle Maintenance — failure to maintain equipment in safe operating condition: brake defects, lighting failures, defective tires, load-securement problems, and other mechanical out-of-service conditions found at roadside.
- Hazardous Materials (HM) Compliance — unsafe handling of hazardous materials: improper placarding, packaging, marking, and loading, applicable only to carriers that transport regulated hazmat.
- Crash Indicator — a history and pattern of crash involvement based on reportable-crash records. This BASIC is not publicly displayed in the same way as the others, because crash data is normalized differently and because preventability is not assessed in the underlying records.
A carrier whose percentile in a BASIC exceeds an intervention threshold is flagged for FMCSA attention, escalating from warning letters to targeted roadside inspections to on-site investigations and, ultimately, enforcement. The system is deliberately prioritization-driven: with millions of carriers and finite inspectors, FMCSA uses SMS to direct its limited oversight capacity toward the carriers whose data suggests the highest crash risk.
Roadside inspections and out-of-service rates
The fuel for SMS is the roadside inspection. State and federal inspectors conduct millions of commercial-vehicle inspections each year, following the standardized levels established by the Commercial Vehicle Safety Alliance (CVSA). A Level I inspection is the most thorough, a full North American Standard inspection of both driver and vehicle; a Level II is a walk-around driver/vehicle inspection; a Level III is a driver-only credential check; and higher levels cover special circumstances such as hazmat and radioactive materials. Every inspection, whether or not it finds a violation, becomes part of the carrier's record and contributes to the exposure denominator that normalizes its BASIC scores.
When an inspection uncovers a serious enough defect — brakes out of adjustment beyond the allowable limit, a fatigued or unlicensed driver, a critical mechanical failure — the inspector issues an out-of-service order on the spot: the vehicle or driver may not move until the violation is corrected. The out-of-service (OOS) rate — the share of a carrier's inspections that resulted in an out-of-service order, computed separately for drivers and for vehicles — is one of the most widely cited single indicators of carrier safety. A carrier with a vehicle OOS rate well above the national average is, on its face, putting unsafe equipment on the road at an elevated rate. National average OOS rates run on the order of roughly one in five vehicle inspections and a smaller share of driver inspections, and FMCSA publishes the national averages so that any individual carrier's rate can be read in context. The QCMobile API exposes a carrier's driver and vehicle OOS rates alongside the corresponding national averages, which is why the worked example below pulls both.
New-entrant audits, SAFER, and chameleon carriers
A carrier does not walk straight from registration into full standing. Every new interstate carrier enters an 18-month new-entrant safety monitoring period, during which it must pass a new-entrant safety audit. The audit — conducted within the first year of operation — reviews the carrier's safety-management controls: its driver-qualification files, hours-of-service records, drug-and-alcohol testing program, vehicle-maintenance records, and accident register. A carrier that fails the audit must remediate or lose its new-entrant registration; failure to fix critical deficiencies results in revocation before the carrier ever attains permanent authority. The new-entrant program is FMCSA's attempt to catch unsafe operators at the front door rather than after a crash.
The public-facing window into all of this is SAFER— the Safety and Fitness Electronic Records system — atsafer.fmcsa.dot.gov. SAFER provides the Company Snapshot, a free per-carrier report keyed to the USDOT or MC number, showing the carrier's census data (name, address, fleet size, operation type), its safety rating, its inspection and crash history summarized over the prior two years, and its operating-authority and insurance status. SAFER is the tool a freight broker, a shipper, or a journalist uses to look up any carrier in seconds. A companion tool, SaferBus, targets the passenger-carrier population so that consumers chartering a bus can check the operator's safety record before booking.
The hardest enforcement problem the census faces is the chameleon carrier — a reincarnated carrier. When an operator accumulates a poor safety record, an out-of-service order, or unpaid penalties, the temptation is to shut down the old USDOT number and re-register under a new one, often with a new name but the same trucks, drivers, management, and address. The new registration arrives with a clean record and re-enters the new-entrant program as if it were a genuinely new business. The Government Accountability Office and the DOT Inspector General have repeatedly documented thousands of such reincarnations, and they are disproportionately associated with carriers that had been ordered out of service. FMCSA combats chameleons with vetting that cross-references new applications against the census for shared addresses, phone numbers, officers, and equipment — precisely the kind of entity-resolution problem that the full census dataset is well suited to. Detecting chameleons is one of the most valuable analytical uses of fmcsa_carriers: clustering registrations on shared identifying attributes surfaces the linkages that a single-record lookup cannot.
Real-world uses of the census
The census is one of the most commercially consequential open federal datasets, because an entire industry of intermediaries depends on it to make daily decisions.
Insurance underwriting. Trucking insurers price policies on a carrier's safety profile, and the census plus the linked inspection, crash, and BASIC data is the raw material. Underwriters pull OOS rates, BASIC percentiles, crash frequency, and fleet size to set premiums and decide whether to write a policy at all. A carrier with deteriorating BASICs or a rising OOS rate is a worsening risk, and insurers monitor the data continuously rather than only at renewal.
Freight broker and shipper vetting. Brokers are legally and reputationally exposed if they tender freight to an unsafe or unauthorized carrier — negligent-selection liability is a live theory in litigation following truck crashes. Before booking a carrier, a broker checks the census for active operating authority, valid insurance on file, and an acceptable safety profile. Load boards and transportation-management systems bake automated SAFER and QCMobile lookups into their carrier-onboarding workflows precisely so that a carrier whose authority has been revoked cannot be booked. The census is, in effect, the trust layer of the freight marketplace.
Safety research and crash causation. Researchers link the census to FMCSA's crash file — which we also hold asfmcsa_crashes — to study what carrier characteristics predict crash involvement. Joining a crash record to the census on USDOT number attaches the carrier's fleet size, operation type, commodity, and safety history to each crash, enabling analysis of whether owner-operators, new entrants, hazmat carriers, or particular fleet-size bands crash at elevated rates. The census is the denominator and the covariate set; the crash file is the outcome.
Market-structure analysis. Economists and industry analysts use the census to map the trucking market: the count of active carriers, the distribution of fleet sizes, entry and exit rates (new USDOT registrations versus deactivations), and the geographic distribution of carriers by state of domicile. The net flow of registrations is a leading indicator of freight-market conditions — surges of single-truck owner-operators registering during a freight boom, and waves of deactivations during a downturn, are visible directly in the census time series. The owner-operator-versus-large-fleet split is itself a structural fact of policy interest, because the two segments have very different safety profiles, cost structures, and regulatory burdens.
Querying the census in Python
There are two practical paths into FMCSA carrier data. For live, per-carrier lookups, FMCSA publishes the QCMobile API, a documented REST service that returns a carrier's census record, BASIC results, operating authority, and OOS rates given a USDOT number, an MC number, or a name search. It requires a free web key, which is registered once and passed as a query parameter. For population-level work, FMCSA publishes bulk snapshots — the SMS download files, the SAFER company census extract, and a regularly refreshed “Motor Carrier Census” dataset on the DOT's open-data portal — each a full-population file you can load into pandas and aggregate.
The workflow below does both: it pulls a single carrier from the QCMobile API and prints its status, fleet size, and OOS rates against the national averages, then loads a bulk census snapshot, restricts it to one state of domicile, and aggregates by operating status and by fleet-size bucket — the owner-operator-versus-fleet structure that characterizes the industry.
import requests, pandas as pd
from collections import Counter
# ---------------------------------------------------------------------------
# FMCSA Motor Carrier Census Analysis
#
# Two complementary data sources:
#
# 1. QCMobile API (live, per-carrier lookups)
# https://mobile.fmcsa.dot.gov/qc/services/carriers/<dot>?webKey=KEY
# Requires a free webKey from https://mobile.fmcsa.dot.gov/QCDevsite/
# Endpoints: /carriers/<dot>, /carriers/<dot>/basics,
# /carriers/name/<name>, /carriers/<dot>/authority
#
# 2. SAFER / Census bulk extract (full-population snapshots)
# https://ai.fmcsa.dot.gov/SMS/Tools/Downloads.aspx (SMS files)
# https://data.transportation.gov/ (Socrata "Motor Carrier Census")
# A pipe/CSV snapshot of every active USDOT number, refreshed monthly.
#
# Fleet-size and operating-status fields are self-reported on the MCS-150
# and may be stale for carriers that have not filed a biennial update.
# ---------------------------------------------------------------------------
WEB_KEY = "YOUR_WEBKEY_HERE"
BASE = "https://mobile.fmcsa.dot.gov/qc/services"
def get_carrier(dot_number):
url = f"{BASE}/carriers/{dot_number}"
r = requests.get(url, params={"webKey": WEB_KEY}, timeout=20)
r.raise_for_status()
return r.json().get("content", {}).get("carrier", {})
# Single-carrier lookup by USDOT number
c = get_carrier(76830) # example DOT number
print(f"Legal name: {c.get('legalName')}")
print(f"DBA name: {c.get('dbaName')}")
print(f"Operating status: {c.get('allowedToOperate')} "
f"(OOS date: {c.get('oosDate')})")
print(f"Power units: {c.get('totalPowerUnits')}")
print(f"Drivers: {c.get('totalDrivers')}")
print(f"Carrier operation: {c.get('carrierOperation', {}).get('carrierOperationDesc')}")
print(f"Driver OOS rate: {c.get('driverOosRate')}% "
f"(natl avg {c.get('driverOosRateNationalAverage')}%)")
print(f"Vehicle OOS rate: {c.get('vehicleOosRate')}% "
f"(natl avg {c.get('vehicleOosRateNationalAverage')}%)")
# ---------------------------------------------------------------------------
# Population-level analysis from the SAFER/Census bulk snapshot.
# Assumes a downloaded CSV named census.csv with the standard column set.
# ---------------------------------------------------------------------------
df = pd.read_csv("census.csv", dtype=str, low_memory=False)
df.columns = [col.strip().upper() for col in df.columns]
# Restrict to a single state of physical domicile
tx = df[df["PHY_STATE"] == "TX"].copy()
print(f"\nTexas-domiciled carriers in snapshot: {len(tx):,}")
# Operating status distribution (active vs out-of-service vs revoked)
status = Counter(tx["STATUS_CODE"].fillna("UNKNOWN"))
print("\nOperating status:")
for code, n in status.most_common():
print(f" {code:<10} {n:>8,}")
# Fleet-size buckets from power-unit counts
tx["PU"] = pd.to_numeric(tx["NBR_POWER_UNIT"], errors="coerce").fillna(0)
def bucket(pu):
if pu <= 1: return "owner-operator (1)"
if pu <= 6: return "small (2-6)"
if pu <= 20: return "medium (7-20)"
if pu <= 100: return "large (21-100)"
return "fleet (100+)"
tx["FLEET"] = tx["PU"].apply(bucket)
order = ["owner-operator (1)", "small (2-6)", "medium (7-20)",
"large (21-100)", "fleet (100+)"]
print("\nFleet-size distribution (active carriers):")
active = tx[tx["STATUS_CODE"] == "A"]
dist = active["FLEET"].value_counts().reindex(order).fillna(0).astype(int)
total = dist.sum()
for label in order:
n = dist[label]
pct = 100 * n / total if total else 0
print(f" {label:<22} {n:>8,} ({pct:4.1f}%)")
A few implementation notes. The QCMobile API nests the carrier object undercontent.carrier in the JSON response, so the helper unwraps that path before returning. The allowedToOperate field is a yes/no flag for current authority, and oosDate is populated only when the carrier is under an out-of-service order, so a null OOS date alongside an affirmative allowedToOperate is the normal active case. The OOS-rate fields and their national-average counterparts come back as numbers already normalized to percentages, which is why the example prints them directly against the averages rather than recomputing.
On the bulk side, reading every column as a string with dtype=str and only then coercing the numeric fields with pd.to_numeric(..., errors='coerce')is the robust pattern, because the census files encode missing fleet counts as blank strings that would otherwise force pandas into mixed-type columns. Operating-status codes in the bulk extract are single letters — A for active is the value the fleet-size distribution filters on — and the exact code set and column names vary slightly between the SMS files and the Socrata census export, so it is worth printing the column list and the status-code distribution once before relying on specific values. Fleet buckets are a modeling choice; the boundaries used here (single-unit owner-operators, small, medium, large, and fleet) reflect the conventional industry segmentation, but the right cut points depend on the question being asked.
Caveats and data-quality limitations
The census is indispensable, but it carries several structural limitations that any serious analysis must account for.
The data is self-reported. Everything on the MCS-150 — fleet size, driver count, operation type, commodities — is declared by the carrier and not independently verified at filing time. Carriers have incentives to under-report or mis-report: a smaller declared fleet can mean lower fees and a different peer group for safety scoring. The numbers should be read as the carrier's own statement of its operation, not as audited fact.
Records go stale. Because fleet and status fields only refresh when the carrier files a biennial update, the census is a patchwork of records of varying ages. A carrier that has not filed in nearly two years carries data that may be badly out of date, and a carrier that quietly ceased operating may sit with an active status until FMCSA deactivates it for a missed cycle. The roughly 2.18 million entities in the file include a very large stock of defunct carriers whose records were never properly closed. Counting “registered carriers” therefore badly overstates the number of carriers actually operating; the active count is far smaller, and even the active count includes recently-defunct operators not yet deactivated. Filtering to active status, and ideally to carriers with recent inspection activity, is necessary to approximate the operating population.
Brokers are not carriers. The census mixes asset-based carriers with non-asset intermediaries — brokers and freight forwarders — that operate no trucks. A broker may hold a USDOT number for identification while its only meaningful registration is brokerage operating authority, and it will report zero or null power units. Treating these entities as carriers, or including them in fleet-size distributions, distorts the picture. Population analysis of the trucking fleet should exclude broker-only and forwarder-only entities by their authority type and entity flags.
Operating authority and USDOT status diverge. As stressed throughout, the safety registration (USDOT number) and the economic registration (MC number / operating authority) have independent lifecycles. An entity can be active on one and revoked or inactive on the other. Any determination of whether a carrier may legally haul for-hire freight requires checking both, plus current insurance on file — not the USDOT status alone. Conflating the two is the most common substantive error in using the dataset for vetting.
Percentile scores are relative and contested. SMS BASIC scores are percentile ranks within a peer group, so a carrier can have a high percentile without an absolutely poor record if its peers are unusually clean, and carriers with too few inspections receive no public percentile at all. The methodology has been the subject of sustained criticism and congressional review over the comparability of scores across carriers of different sizes and the public display of certain BASICs; FMCSA has revised the system over time. Scores are a prioritization signal, not a precise safety ranking, and should be interpreted as such.
Related writing
NHTSA vehicle safety complaints: the database behind auto defect investigations and recalls — the consumer-complaint and defect-investigation system for passenger vehicles, the highway-safety counterpart to FMCSA's carrier-level oversight, where complaint patterns rather than roadside inspections drive enforcement.
PHMSA pipeline safety data: the federal database behind gas and liquid pipeline incidents — the sister DOT modal agency for pipelines and hazardous materials, sharing jurisdiction with FMCSA over hazmat transport and built on the same model of mandatory reporting, consequence thresholds, and operator-keyed safety records.
The FAA Civil Aviation Registry: every registered aircraft and certified airman — the aviation analogue to the motor carrier census, a federal registration master file keyed to unique identifiers that anchors an entire mode's safety, certification, and enforcement data.
FMCSA crash data: the database behind large truck and bus crashes — the crash side of the same MCMIS system, keyed to the carrier USDOT number from this census, feeding the CSA Crash Indicator safety score.