The Arizona Department of Transportation approved $11 million to resurface Interstate 15 between the Virgin River and Utah border in the northwest section of the state.
The route is crucial to commuters and commercial truck drivers traveling between Nevada and Utah, and drivers recently have complained about the highway's poor condition.
"Mohave County's portion of the interstate is a key artery to the economic health of the western United States," said Buster Johnson, the chairman of the Mohave County Board of Supervisors.
"There are many fronts in the battle for economic development and recovery. The I-15 corridor links major markets such as Salt Lake City, Las Vegas and Los Angeles."
The Arizona agency, with the Nevada and Utah departments of transportation, recently filed for federal grant money to repair a bridge over the Virgin River at mile marker 16.
Transportation officials in Arizona said $250 million for improvements is needed on the 30-mile stretch of the interstate that winds through the Virgin River Gorge.
To generate the funding to repair the highway, the state in October submitted an application with the Federal Highway Administration to make a portion of Interstate 15 a toll road.
Arizona's request was denied in February after the federal government decided to use highways in North Carolina, Missouri and Virginia in its pilot program.
If one of those states drops out of the program, the Arizona stretch of I-15 between Nevada and Utah could be reconsidered.