Union City is a city in Alameda County, California, United States in the San Francisco Bay Area. It is located approximately 19 miles (31 km) south of Oakland, 30 miles (48 km) from San Francisco, and 20 miles (32 km) north of San Jose. It was incorporated in 1959, combining the communities of Alvarado and Decoto. The city has 72,000 residents across a diverse population. Alvarado is a California Historical Landmark (#503). The city celebrated its 50th anniversary in 2009.

Union City station is a Bay Area Rapid Transit (BART) station in Union City, California. The station sits near Decoto Road east of Alvarado-Niles Road, directly behind the James Logan High School campus. The station is served by the Orange and Green lines. Local bus service is provided by Union City Transit and AC Transit.