State Route 85 is a 128.86-mile-long (207.38 km) state highway in the U.S. state of Arizona. The highway runs from the United States–Mexico border near Lukeville to the north ending at Interstate 10 (I-10) in Buckeye. The highway also intersects I-8 in Gila Bend and serves as a connector between I-8 and I-10 and for travelers between Phoenix and Yuma as well as San Diego. SR 85 between I-10 and I-8, as well as I-8 between SR 85 and I-10 in Casa Grande, is touted as a bypass of the Phoenix area for long-distance travelers on I-10.

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.