Union City is a city in Alameda County, in California's East Bay, situated along the Interstate 880 corridor roughly 19 miles south of Oakland and 30 miles southeast of San Francisco. With a population of 70,143 at the 2020 census, it forms the Tri-Cities area with neighboring Fremont and Newark, bounded by Hayward to the north. The city's modern identity began in 1959, when the communities of Alvarado, Decoto, and New Haven incorporated together as Union City. Alvarado had earlier served as the original county seat of Alameda County, and the site of its first courthouse remains a California Historical Landmark. Railroad lines and industrial corridors historically divided the east and west sides of the city, a pattern that still shapes its neighborhoods. Union City's greatest asset is its transportation access. The Union City BART station, served by the Orange and Green lines, sits near the Decoto area behind James Logan High School and connects residents directly to San Francisco, Oakland, and San Jose. That rail link, combined with Interstate 880, makes the city a practical home base for commuters across the Bay Area. The community is notably diverse and family-oriented, with a dense-suburban feel, a strong restaurant and coffee-shop scene, and an extensive parks system, including Union Landing's shopping and entertainment district. Public education is provided by the New Haven Unified School District, anchored by James Logan High School. For people seeking East Bay convenience, BART access, and a diverse, well-established community with more attainable housing than neighboring Fremont, Union City offers a compelling balance of suburban living and regional connectivity.