Milpitas, California (US) Location Located in Santa Clara County, south San Francisco Bay Area, California 37n26 (Latitude), 121w54 (Longitude) 13.6 square miles in area Get Directions Click here or on the map to be able to zoom in or out, or get directions. Santa Clara County Quick Facts from the Census Silicon Valley is defined as being Santa Clara County, at the southern tip of the San Francisco Bay. Milpitas is located on the east side, north end, just south of Fremont, which is in Alameda County. East of of Milpitas is unincorporated ranch land and wilderness. Click the little insert to get an aerial view of Milpitas, or on…