I start with the totals because they are easy to misread. Across the 39 months in this dataset, August 2023 through October 2026, Montana recorded 85,975 roadside inspections and 80,554 violations. A state that size sees a lot of trucks, and the summary numbers hide a lot. Before anyone decides whether Montana is a tough enforcement state or a state with an unusual truck mix, the breakdown has to be read carefully. The Montana insights page collects these figures in one place if you want to follow along.
The headline rate
Montana's out-of-service rate is 22.7 percent. The national rate over the same window is 17.6 percent. That is the number that makes headlines, so it deserves a precise definition. The 22.7 figure is out-of-service violations divided by total violations: 18,281 out of 80,554. It is not the share of trucks that were parked. A second measure is the out-of-service count per inspection, which is 21.3 percent for Montana.
Violations per inspection come to 0.94 in Montana. Nationally the same division gives about 1.60. So Montana writes fewer violations per stop, but a larger fraction of the ones it writes are out-of-service. Those two facts together point toward the severity mix of what gets cited, not toward more total paperwork.
Where the gap sits
Out-of-service status is assigned violation by violation, based on the criteria in the federal rules. Two categories in Montana's data stand out.
Vehicle violations: Montana logged 18,375 vehicle violations, and 12,680 of them were out-of-service. That is 69.0 percent. The national vehicle figure works out to about 24.0 percent (1,703,633 of 7,100,282).
Driver violations: Montana logged 8,830 driver violations, with 5,601 out-of-service, or 63.4 percent. Nationally, about 24.1 percent of driver violations were out-of-service (565,351 of 2,344,141).
I want to be careful with what those shares mean. A high out-of-service share in a category means that when inspectors wrote something in that category, they were more likely to place it out of service. It can reflect what trucks were actually carrying into Montana. It can also reflect inspector judgment, the local enforcement emphasis, and which carriers were selected for inspection. The data here cannot separate those causes. Anyone who tells you the number proves the trucks are worse, or proves the state is harsher, is claiming more than the table shows.
What I can say plainly is that both categories sit far above the national share. The driver side is notable because it is a smaller pool with a much larger relative gap. Vehicle out-of-service counts are larger in absolute terms, but the driver gap is the one that changes most from the national baseline.
Hazmat is a small sample
Montana logged 160 hazardous materials violations, 30 of them out-of-service, which is 18.8 percent. Nationally the figure is 26.6 percent (15,088 of 56,752). Montana is below the national rate here, but 160 violations across 39 months is a small count. A handful of inspections can move that percentage a lot. I would not build a policy conclusion on it.
What the numbers do not tell you
Three cautions belong in any reading of this table.
First, the categories I broke out do not add up to the totals. Driver, vehicle, and hazmat violations together come to 27,365 of Montana's 80,554. The rest sit in categories this breakdown does not cover, so I am not making claims about them.
Second, an out-of-service placement is an enforcement action, not a crash forecast. It tells you what the inspector found and how they classified it. Linking it to crash risk takes a different dataset and a different analysis.
Third, inspection selection is not random. Carrier history, corridor, and inspector discretion all shape who gets stopped. Comparing one state's rate to the national average without those controls tells you where to look, not what caused the difference.
Key takeaways
- Montana's out-of-service rate is 22.7 percent against a national 17.6 percent, measured as out-of-service violations over total violations.
- Both driver (63.4 percent) and vehicle (69.0 percent) out-of-service shares sit well above national levels.
- The hazmat sample is too small to read closely.
- High out-of-service shares reflect what gets cited and how it is classified, as well as what is on the road. The data does not settle the cause.
If you want to check how a specific violation is classified before you draw a conclusion from it, start with the map and the insights index. Reading the classification rules alongside the numbers is what keeps a rate from turning into a story.