The United States Postal Service is testing what just might be the future of delivery in Arizona and Texas. The agency said it will be participating in a pilot program that will see self-driving semi-trucks hauling USPS trailers between its Phoenix and Dallas distribution centers.

The trucks will be run by TuSimple, a San Diego-based global self-driving company that actually operates trucks out of Tucson. The company announced Tuesday it had been awarded the contract by the USPS.

USPS said the pilot program was just “one of many ways” its “innovating and investing” in the future. The agency is exploring ways that autonomous vehicles could improve safety and delivery efficiency on longer hauls.

“We are conducting research and testing as part of our efforts to operate a future class of vehicles which will incorporate new technology to accommodate a diverse mail mix, enhance safety, improve service, reduce emissions, and produce operational savings,” the agency said in a statement.

As part of its contract with the USPS, TuSimple will conduct five round trips starting in May between Phoenix and Dallas during a two-week pilot program. According to a release, a series of the company’s self-driving trucks will run for 22 hours each, including overnight, traveling through Arizona, New Mexico and Texas along the Interstate 10, Interstate 20 and Interstate 30 corridors.

“This new route is an important milestone as TuSimple scales its autonomous operations beyond Arizona and marks the company’s self-driving debut into Texas,” the company said in a release.

The company said long-haul routes like this with short turnaround times are “well suited for self-driving trucks” because this kind of route would usually require driving teams of two. Its goal is to free human drivers up to focus on the shorter routes. The company said its autonomous trucks were safer because “they can see more and react faster than humans — rain or shine, day or night.”

A safety engineer and a driver will be on board the truck during the entire pilot program, according to both USPS and TuSimple, in order to “monitor vehicle performance and to ensure public safety.”