SR 186 begins at the United States–Mexico border (near Avenue International) in the community of Los Algodones.

The route heads to the northeast along the Alamo Canal and crosses the center of the Fort Yuma-Quechan Reservation.

SR 186 continues northward to an interchange with I-8 in Araz Junction, where the route terminates at the northbound ramps.

[7] A road south from the Ocean-to-Ocean Highway to the Mexican border just west of the Colorado River existed by 1917,[8] and was paved between 1956 and 1965.

The bridge is 140.09 feet (42.70 m) long, and is considered unable to sustain the traffic it was designed to handle.