Vallejo is located on the southwestern edge of Solano County, California in the North Bay region of the San Francisco Bay Area in Northern California. Vallejo is accessible by Interstate 80 between San Francisco and Sacramento, and is the location for the northern half of the Carquinez Bridge. It is also accessible by Interstate 780 from neighboring Benicia to the east, and by Route 37 from Marin County to the west. Route 29 (former U.S. Route 40) begins in the city near the Carquinez Bridge and travels north through the heart of the city and beyond into Napa County, entering neighboring American Canyon and eventually Napa.