Business Loop I-5 - San Diego, Del Mar, Solana Beach, Encinitas (Leucadia/ Cardiff), Carlsbad and Oceanside

Included in the route of San Diego County Route S21 (Torrey Pines Road, Camino del Mar, Coast Highway 101, Carlsbad Boulevard, and Coast Highway), this former business route traveled along the original U.S. 101 alignment. Early map appearances included early 1960s ACSC (Auto Club of Southern California, a branch of the national AAA) maps, especially when the freeway only bypassed Oceanside and Carlsbad as far south as Palomar Airport Road (San Diego County Route S12). A mid 1960s Automobile Club Association of Southern California map showed portions of former Business Loop I-5 along what is now Historic U.S. 101 (Coast Highway) through Oceanside and Carlsbad. A remnant of this long business route is perhaps the Solana Beach business loop.