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FreightWaves Classics/Infrastructure: I-40 is a key east-west highway

This is the latest in an intermittent FreightWaves Classics series about the U.S. Interstate Highway System (IHS). The series began with a profile of Interstate 2 (I-2) and has covered each interstate in numerical order. Today’s article profiles Interstate 40 (I-40), which runs from North Carolina in the East to California in the West. Earlier articles can be found on


I-40 is one of the interstate highways that was in the original IHS plan. Spanning eight states, it is a major automotive and trucking transportation corridor that travels generally in an east-west direction, connecting the Southeast and the Desert Southwest. 

Interstate 40 is the third-longest interstate highway in the nation (after I-90 and I-80). Its western end is at I-15 in Barstow, California, while its eastern terminus is at a concurrency of U.S. Route 117 (US 117) and North Carolina Highway 132 (NC 132) in Wilmington, North Carolina. 

If driving its entire length at an average of 60 miles per hour, it would take 43 hours to drive the 2,555 miles of Interstate 40. The highway runs through or near a number of major cities, including Albuquerque, New Mexico; Amarillo, Texas; Oklahoma City, Oklahoma; Little Rock, Arkansas; Memphis, Nashville and Knoxville, Tennessee; and Greensboro, and Raleigh, North Carolina.

In five states (Arizona, New Mexico, Texas, Oklahoma and Arkansas) the speed limit on I-40 is 75 mph instead of the 70 mph limit in California, Tennessee and North Carolina.

A map of I-40's route across the United States. (Image:
A map of I-40’s route across the United States. (Image:


For about 1,000 miles of its length, I-40 follows the general route of Beale’s Wagon Road from Arkansas to California. Beale’s Wagon Road was built prior to the Civil War (1857-1859) by a team led by U.S. Army Lt. Edward Fitzgerald Beale using a team of camels as pack animals.

In addition, beginning in Barstow, I-40 generally follows the alignment of Historic U.S. 66 across the Mojave Desert into the high desert, spans the Colorado River west of Kingman, Arizona, and gains elevation on a course south of the Grand Canyon to Flagstaff, Arizona. I-40 continues on or near the route of Route 66 to Oklahoma City. East of Oklahoma City, I-40’s route generally parallels US 64 and US 70.

A Route 66 sign in Arizona. (Photo:
A Route 66 sign in Arizona. (Photo:

Here is an interesting note that we should all feel lucky that it did not come to pass… The U.S. government considered a plan from 1963 to 1966 to use atomic bombs to excavate a path for I-40 through California. However (and luckily), the plan was not adopted because of the cost of developing the explosives and a “clean bomb” was unavailable.

The last section of I-40, which connected Wilmington to Raleigh, was completed in the late 1980s. At that time, commentator Charles Kuralt stated: “Thanks to the interstate highway system, it is now possible to travel from coast to coast without seeing anything.”

I-40 in California

In California, I-40 runs through the sparsely populated western part of the state’s Inland Empire region. Heading east from Barstow (and a junction with I-15), I-40 runs across the Mojave Desert in San Bernardino County to Needles, and then crosses into Arizona southwest of Kingman. In California, I-40’s length is 155 miles. 

I-40 in Arizona

In Arizona, I-40 is a key route to the Grand Canyon’s South Rim; exits from the highway lead into Grand Canyon National Park in both Williams and Flagstaff. The interstate runs 359 miles in Arizona, and west of Flagstaff, is at its highest elevation (the road crosses just over 7,320 feet). In addition, I-40 passes through the Navajo Nation, the largest Indian reservation in the country. 

I-40 in New Mexico

I-40 runs across the width of New Mexico, a distance of 374 miles. Among the state’s cities along I-40’s route are Gallup, Grants, Albuquerque, Santa Rosa and Tucumcari. In addition, I-40 travels through several Indian reservations in the western half of New Mexico. The highway reaches its highest point in the state (7,275 feet) between Gallup and Grants at the Continental Divide.

A New Mexico marker notes the Continental Divide. (Photo:
A New Mexico marker notes the Continental Divide. (Photo:

I-40 in Texas

In the sparsely populated west Texas panhandle, several ranch roads connect directly to I-40. Amarillo is the only major city in Texas that is directly served by I-40. However, I-40 connects with I-27 (south toward Lubbock) and US 287 (south to Dallas/Fort Worth). In Texas, I-40’s length is only 177 miles.

I-40 in Oklahoma

I-40 runs through the heart of Oklahoma, and passes through quite a few of the state’s cities and towns. The interstate’s length in Oklahoma is 331 miles.

I-40 in Arkansas

The interstate enters west-central Arkansas and runs for 285 miles in the state. The route intersects southbound I-540/US 71, which leads to Fort Smith. I-40 continues east and intersects I-49 (which runs north to Fayetteville). It then runs through the Ozark Mountains, and turns south to North Little Rock, and then east to West Memphis. I-40 briefly runs concurrently with I-55 in West Memphis; it then crosses the Mississippi River via the Hernando de Soto Bridge and enters Memphis, Tennessee.

A truck on I-40 in Tennessee. (Photo:
A truck on I-40 in Tennessee. (Photo:

I-40 in Tennessee

I-40’s longest stretch is in Tennessee (455 miles). It runs through each of the state’s three “Grand Divisions,” as well as its three largest cities (Memphis, Nashville and Knoxville), as well as several other cities in the state. Before leaving Tennessee, I-40 enters the Great Smoky Mountains and heads toward North Carolina.

I-40 in North Carolina

I-40’s length in North Carolina is 420 miles, second only to Tennessee. It enters western North Carolina “as a winding mountain freeway through the Great Smoky Mountains.” Unfortunately, I-40 often closes because of landslides and/or weather conditions. The interstate runs primarily north-south as it enters the state, and then shifts to an east-west alignment after merging with US 74 at the eastern end of the Great Smoky Mountains Expressway. From there, I-40 runs through Asheville, Hickory and Statesville, and then the Piedmont Triad. Just east of Greensboro I-40 and I-85 merge. The two interstate highways split west of the Research Triangle area, passing through Durham and Raleigh. From the Triangle to its eastern end in Wilmington, I-40 again runs in a generally north-south direction.

The I-40 bridge after it collapsed into the Arkansas River in 2002. (Photo: Xpda/Wikipedia)
The I-40 bridge after it collapsed into the Arkansas River in 2002. (Photo: Xpda/Wikipedia)

Major accidents along I-40’s route

On the morning of May 26, 2002, two barges moving upstream in the Arkansas River struck pier supports for the I-40 bridge near Webber Falls, Oklahoma. The barges were outside the river’s marked channel when the accident took place. The collision caused a 580-foot section of the I-40 bridge to drop into the river. Cars and trucks also fell into the water, and 14 people died.

As noted above, landslides are common occurrences in the Pigeon River Gorge section of I-40 along the Tennessee-North Carolina border. When it was being built, I-40’s roadway was cut into the slopes of several steep mountains. In addition, vehicle accidents are also common on the winding road, particularly during bad weather. 

On May 11, 2021, the Hernando de Soto Bridge, which carries I-40 over the Mississippi River, was closed when a major split was discovered in one of the bridge members.

Interstate 40 is almost a coast-to-coast interstate, and certainly traverses some very diverse states.