Oceanside-Escondido Freeway / San Pasqual Road / Julian Highway
Runs from I-5 in Oceanside to I-10 in Blythe
State 78 passes through a very diverse region. Starting near the ocean in Oceanside as a busy freeway, the 78 is well known for being a congested roadway during peak times from Oceanside to Escondido. East of Escondido, however, the roadway quickly downgrades to a two-lane roadway.
Between Escondido and Ramona, the highway passes through farmlands and orchards before ascending a steep and winding grade just east of San Pasqual. This section is prone to closures because of the geology. Large boulders, weak and fractures bedrock, as well as a steep slope all conspire to bring debris onto the roadway. Limited passing areas also make this section more congested with trucks and other heavy vehicles driving slowly up the grade.
From Ramona to Julian, the route runs through canyons and scenic mountains. Beyond Julian, the road drops down into the desert by descending Banner Grade.
East of Banner Grade, State 78 passes through Anza Borrego State Park. This section is also quite popular with off-road enthusiasts, particularly in spring and fall when temperatures are lower. After passing through a rather bleak and desolate section of desert, 78 joins briefly with State 86, heading south, then east via Westmoreland and the Brawley Bypass.