Interstate 805 (I-805) is a major north–south auxiliary Interstate Highway in Southern California.It is a bypass auxiliary route of I-5, running roughly through the center of the Greater San Diego region from San Ysidro (part of the city of San Diego) near the Mexico–U.S. border to near Del Mar.The southern terminus of I-805 at I-5 in San Ysidro is less than 1 mi (1.6 km) north of the …