Tracy is the second most populated city in San Joaquin County, California, United States. The population was 93,000 at the 2020 census. Tracy …Tracy is the second most populated city in San Joaquin County, California, United States. The population was 93,000 at the 2020 census. Tracy is located inside a geographic triangle formed by Interstate 205 on the north side of the city, Interstate 5 to the east, and Interstate 580 to the southwest.