The original highway from Casa Grande to Tucson entered the Old Pueblo via Miracle Mile, a road modeled after German Autobahns but without overpasses or an exclusive right of way. Traffic circles at either end of Miracle Mile were the best Tucson could come up with in 1937. The section of Miracle Mile West stretching between Miracle Mile and the Southern Pacific overpass was signed as Business Loop 10, SR 84 and SR 93 in the 1960s. It is now marked as the southern leg on SR 77, the new designation for US 80/US 89 north out of Tucson. The Business Loop designation was dropped in 1998.