Union City is a city located in the San Francisco Bay Area of California, United States. It is situated in Alameda County and is part of the East Bay region. Union City is bordered by Hayward to the north, Fremont to the south, and the San Francisco Bay to the west. The city has a population of approximately 74,000 people as of 2021. Union City is known for its diverse community, thriving business sectors, and access to recreational areas such as the Don Edwards San Francisco Bay National Wildlife Refuge.