Interstate business routes are roads connecting a central or commercial district of a city or town with an Interstate bypass. These roads typically follow along local streets often along a former US route or state highway that had been replaced by an Interstate. Interstate business route reassurance markers are signed as either loops or spurs using a green shield shaped and numbered like the shield of the parent Interstate highway.

State Route 186 is a highway in Cochise County, Arizona that runs from its junction with Interstate 10 in Willcox to its junction with SR 181 west of the Chiricahua National Monument. It is a northwest–southeast diagonal route.