The 37-mile State Route 85 corridor – which provides a major north-south connection between Interstate 10 and Interstate 8 – serves an important role in both interstate travel and intrastate travel between the Phoenix region and the growing communities of Gila Bend and Yuma. It also allows traffic using I-10 to bypass the urban core of the Phoenix region.

State Route 85 is classified as a rural arterial highway in the State Highway System and a principal arterial highway on the National Highway System.

The highway serves as a major link between the Phoenix metropolitan region and the San Diego metropolitan region, as well as an interstate trucking route to access the major international ports in the Los Angeles region. SR 85 and Business 8 are also designated sections of the future proposed Canada-America-Mexico (CANAMEX) trade route.

Widely used by both private and commercial vehicles, SR 85 remains the only two-lane portion of the route between Phoenix and San Diego. Traffic volumes on SR 85 are expected to double in less than 20 years.

ADOT completed a Design Concept Report and Environmental Assessment in 2002 that recommended solutions to upgrade SR 85 from a two-lane undivided highway to a four-lane, access-controlled divided highway to address transportation and safety needs on SR 85 and B-8. Due to the significant challenges of obtaining timely funding to construct the ultimate access-controlled roadway, a phased implementation plan was developed that would achieve the goal of providing a four-lane divided highway in the short-term, while still supporting the long-range transportation goals of the recommended ultimate access-controlled roadway.

An Access Management Study has also been completed for the SR 85 and B-8 corridors to balance the flow of traffic and access to adjacent business and residential development.

ADOT is currently in the process of improving SR 85 from a two-lane highway to a four-lane divided highway, as identified in the phased implementation plan, with most of the widening work to date occurring south of the Gila River to Gila Bend.

Some projects have recently been completed to improve the SR 85 corridor and other improvement projects are planned. Please see the Improvements section for more information about completed and planned improvements on SR 85.