Site Navigation Baja California California Colorado Idaho Hawaii Nevada New Mexico Oregon Utah Washington Wyoming     California 78 Routing California 78 is a major east-west route, starting at Interstate 5 in Oceanside and leading east through the inland valleys of San Diego County, over the Laguna Mountains separating the coastal areas from the desert, and through the vast Imperial Valley. The highway ends at its junction with Interstate 10 in Blythe, just shy of the Arizona State Line. Through the busy corridor between Oceanside and Escondido via Vista, California 78 is a freeway, with its first sections constructed in 1958. It downgrades to a two-lane conventional highway just east of Escondido, serving the communities of Ramona, Santa Ysabel, Julian, and Banner before entering Anza-Borrego Desert State Park. California 78 continues east through here, merging with California 86 (old U.S. 99) before splitting 24 miles further southeast, at Brawley. East of Brawley, California 78 resumes its lonely trek, passing by the famous Glamis Sand Dunes before turning northeast. California 78 is headed nearly due north when it finally reaches its end at Junction Interstate 10; travelers may continue straight ahead onto Business Loop I-10 to reach the services of Blythe. Highway Guides Index Eastbound Westbound Scenes Pertaining to California 78 Page Updated July 9, 2009.