I-40's Deadliest Truck Miles Are the 82 Leading Into Flagstaff

The Finding

Interstate 40 runs 360 miles across northern Arizona, from the Colorado River through Kingman, Flagstaff, Winslow, and Holbrook to the New Mexico line. It’s the state’s main east to west freight route north of Phoenix.

I counted every fatal crash involving a large truck on the I-40 mainline from 2015 to 2024. There were 118, and they killed 139 people.

The 82 miles leading into and through Flagstaff, under a quarter of the road, carried 36 of those crashes and 46 of the deaths.

That stretch climbs out of the high desert into the pines and through Flagstaff to the east edge of town. For a decade it ran the highest truck death rate anywhere on I-40 in Arizona.

How I Counted

The crash records come from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System, the federal census of every fatal crash on a US public road.

I pulled Arizona fatal crashes from 2015 to 2024 that involved a large truck, meaning a vehicle FARS codes as a medium or heavy truck. Then I kept the crashes recorded on the I-40 mainline and left out ramps and exits. One more crash had no usable location, and I left it out too.

The milepost field in the federal file is coded inconsistently from year to year. So I placed each crash on the highway by its recorded latitude and longitude, using the Arizona Department of Transportation’s own milepost markers.

To compare stretches fairly, I divided deaths by truck miles traveled. Truck traffic comes from ADOT’s 2024 federal highway inventory, applied across all ten years. Truck volumes shift over a decade, so treat each rate as an estimate and the comparison between stretches as the point.

The federal record covers fatal crashes only, and it says nothing about fault. ADOT’s own crash records also cover crashes where people were hurt but survived. I’ll add them to this piece when they come in.

Seven Stretches, Two Standouts

I split I-40 into six stretches by the towns most drivers know. Measured against truck traffic, the miles leading into Flagstaff stand apart.

The 82 miles west of Flagstaff, through town to its east edge, recorded 46 deaths. That works out to about 1.78 per 100 million truck miles.

The open miles east of Kingman ran the lowest rate on the road, about 0.54. The rest of I-40 fell between 0.96 and 1.30.

Source: NHTSA FARS 2015-2024. ADOT HPMS 2024 truck AADT. Rates are estimates. Computed by AZ Law Now.

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That stretch also logged the most fatal truck crashes, 36 in 82 miles. The open miles east of Kingman logged 8 in 64.

Half of I-40’s Fatal Crashes Involve a Big Rig

Across Arizona, large trucks were involved in about 11% of fatal crashes from 2015 to 2024. On I-40 the share was 47%. Trucks were in 118 of the road’s 249 fatal crashes, and those crashes accounted for 139 of its 298 deaths.

That tracks with who uses the road. ADOT’s 2024 counts put trucks at about 45% of all traffic on I-40 in Arizona, and above half on the stretch from Flagstaff to Winslow.

For anyone driving a car between Kingman and Holbrook, that means sharing two lanes each way with a steady stream of semis. ADOT’s inventory shows I-40 at two lanes in each direction for all 360 miles.

The Climb West of Flagstaff

Two 10-mile pieces of I-40 stand out on the map. Each recorded 12 deaths, more than any other 10 miles on the route.

The first sits about 40 miles west of Flagstaff, between mileposts 150 and 160. Eight fatal truck crashes happened there, and they killed 12 people.

Eleven of those 12 weren’t in the truck. Eight of the 14 fatal crashes of any kind on those 10 miles involved a big rig.

ADOT’s inventory grades about 7 of those 10 miles at 2.5% or steeper. Across all of I-40 in Arizona, about one mile in eight is that steep.

Source: NHTSA FARS 2015-2024, located by coordinates on ADOT mileposts. Computed by AZ Law Now.

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The data doesn’t say the grade caused these crashes. Police recorded 5 of the 14 trucks involved on a slope and 7 on level road. It does show that the steepest stretch of I-40 was also one of its two deadliest.

Through Flagstaff

The second cluster runs through Flagstaff itself. Across the 12 miles between mileposts 190 and 202, from the west edge of town past the I-17 interchange, 11 fatal truck crashes killed 13 people and injured 20 more.

This is where I-40 freight meets traffic coming up I-17 from Phoenix. Nine of the 13 people killed there were outside the truck.

In the Dark, From Behind, Head-On

Most of I-40 is unlit, and the crash record shows it. 63 of the 118 fatal truck crashes happened in the dark, and they killed 72 people.

Rear-end collisions were the most common kind, with 38 crashes and 43 deaths. Another 16 crashes were head-on or opposite-direction sideswipes on a divided interstate, and they killed 19.

Most of these crashes happened on dry pavement. 17 of the 118 involved a vehicle on wet, icy, or snowy road.

Most of the Dead Weren’t in the Truck

Of the 139 people killed, 87 were outside the truck. They were drivers and passengers in other vehicles, and 12 were pedestrians. Fifty-two were riding in a large truck.

These crashes also left survivors. Another 139 people were hurt, 36 of them recorded with suspected serious injuries.

The toll is climbing. From 2015 to 2019, I-40 recorded 48 fatal truck crashes and 54 deaths. From 2020 to 2024 it recorded 70 crashes and 85 deaths, with 27 in 2022 alone.

Trucks From Somewhere Else

Of the 153 large trucks in these crashes, 143 were registered outside Arizona. California registrations led with 61.

Registration shows where a truck is plated, not where its owner operates. Still, the record fits a road that moves freight between the West Coast and the rest of the country.

Fatigue and Out-of-Service Orders

ADOT’s 2024 statewide truck parking study reviewed five years of truck crashes, from July 2018 to July 2023. It found 158 crashes on I-40 tied to driver fatigue or trucks parked where they shouldn’t be, more than any other corridor in Arizona.

Federal inspection records point the same way. From October 2023 to September 2026, 20,311 roadside inspections were logged at I-40 towns and ports of entry. About 1 in 5 drivers inspected there was ordered out of service, against about 1 in 8 elsewhere in Arizona.

A driver out-of-service order takes the driver off the road on the spot, for problems such as hours-of-service and licensing violations. At the Sanders port of entry near the New Mexico line, inspectors ordered 1,972 of 3,119 inspected vehicles out of service for equipment problems.

What This Means

A truck crash on I-40 is rarely just a truck’s problem. Most of the people who die are in the cars around the truck, and most of the trucks are registered out of state.

The records that explain a crash like that sit in several places. The police report, the driver’s logs, the truck’s federal inspection history, and the carrier’s safety file each hold part of the story.

If a commercial truck hit you or someone you love on I-40, talk to our truck crash lawyers before you talk to the trucking company’s insurer. The first conversation is free.

For a decade, the deadliest truck miles on I-40 were the 82 leading into Flagstaff.

Related Coverage

For the legal and process context, see Ron DeBrigida’s guide to Arizona truck crash law and Stephanie Ramirez’s truck crash action plan.

For the freight route across southern Arizona, see how I-10 truck crash deaths rose 76% from Quartzsite to the New Mexico line.

For the route from Phoenix up to Flagstaff, see where I-17 truck crash deaths cluster past Anthem and Black Canyon City. For the rules meant to keep tired truckers off the road, see fatigued truckers and Arizona’s hours-of-service data. And for the statewide picture, see our investigation of the Arizona truck death surge.

For the road from Wickenburg to Kingman and Hoover Dam, see why US-93’s deadliest truck miles are two lanes north of Wickenburg.