In the U.S. state of Arizona, Interstate 10 (I‑10), the major east–west Interstate Highway in the United States Sun Belt, runs east from California, enters Arizona near the town of Ehrenberg and continues through Phoenix and Tucson and exits at the border with New Mexico near San Simon. The highway also runs through the cities of Casa Grande, Eloy, and Marana. Segments of the highway are referred to as either the Papago Freeway, Inner Loop, or Maricopa Freeway within the Phoenix area and the Pearl Harbor Memorial Highway outside metro Phoenix.
Route description
I-10 through Arizona is designated a "Purple Heart Trail", after those wounded in combat who receive the Purple Heart. The western terminus is located at the California border at the Colorado River in La Paz County where I-10 continues westward into California towards Los Angeles. Here, the same physical road is signed as both I‑10 and U.S. Route 95 (US 95).
Western segment
The highway runs east by northeast through Ehrenberg, the Dome Rock Mountains, and Quartzsite and then turns to an east by southeast orientation just before the junction for US 60. It continues this path entering Maricopa County and the Phoenix Metro area. The route turns east by northeast again at the junction for State Route 85 (SR 85) northwest of downtown Buckeye, and turns due east at Verrado Way (exit 120). Here, the speed limit drops from . The landscape by this point is largely urban.
Papago Freeway
From there, I-10 traverses through the communities of Goodyear, Avondale, and Tolleson, meeting with local streets and area freeways such as Loop 303 (at the former Cotton Lane interchange, exit 124) and the Loop 101 Agua Fria Freeway along the way. By December 2019, the simple diamond interchange with 59th Avenue (exit 138) was totally rebuilt, transforming it into the first of two junctions with the Loop 202 Ed Pastor Freeway. As it makes its way through Phoenix, the highway meets with I‑17 and US 60 for the first time just northwest of downtown at The Stack.
Inner Loop
East of The Stack, I-10 forms the north edge of downtown. Near 3rd Avenue, the highway enters a half-mile tunnel () that runs under a park and the central branch of the City of Phoenix Library. Emerging past 3rd Street, the highway continues due eastward for another before coming to another interchange for Route 51 and Loop 202 (second of three junctions with the latter), called the Mini Stack. At this interchange, I‑10 turns southward for about , passing near Sky Harbor Airport and reaching the second junction with I‑17/US 60. Here, I‑17 terminates as I‑10 skews eastward again. After this junction, the highway is cosigned with US 60.
Maricopa Freeway
Continuing southeast over the Salt River and eastward, I‑10 and US 60 enter Tempe and meets with SR 143. Then, at the Broadway Curve, the freeway turns southward again, with US 60 splitting off to become its own freeway. I‑10 continues southward running along the city borders of Phoenix on the west, and Tempe, Guadalupe, Tempe again, and finally Chandler on the east. Immediately north of the Gila River Indian Community, I‑10 has its third and final intersection with Loop 202. Past Loop 202, the highway turns to a more south by southeast direction going through the Gila River Indian Community and entering Pinal County.
Broadway Curve
As of a 2006 estimate, the Broadway Curve portion of I‑10 in Tempe carries an average of 294,000 vehicles per day. This number is predicted to increase by over 150,000 to approximately 450,000 by 2025. This section of I‑10 is currently twelve lanes wide, and is the widest section of freeway in the valley. Construction is underway (as of July 2021) to widen the Broadway Curve area.
Eastern segment
After exiting the Phoenix metropolitan area, I‑10 continues southward into Casa Grande intersecting I‑8 before heading southeast towards Tucson, paralleling the Santa Cruz River. Several projects have occurred recently, including construction of a new exit at Twin Peaks Rd in Marana and widening of I‑10 from Prince Rd to I-19 in Tucson to four lanes in each direction, which was later extended to Ruthrauff Rd/El Camino Del Cerro. After I-10's junction with I-19, I-10 heads southeast towards Benson and Willcox before entering New Mexico.