 Before the designation of SR 78, a road known as the Brawley-Westmorland-Julian-Oceanside Highway (connecting Oceanside, Escondido, Ramona, Julian, Westmorland, and Brawley) existed during the early twentieth century. This road roughly followed the current routing of SR 78 from Escondido to the east of Brawley, although it traveled along a different routing from Westmorland into Brawley. No road connected Brawley with Glamis in 1919; it was necessary to travel north through Calipatria to reach Blythe. East of the Sand Hills, there was a road from Glamis passing by Smith Well into Palo Verde, which roughly follows the routing of SR 78.
