Union City is a borough in Erie County, Pennsylvania, United States. It is located 22 miles (35 km) southeast of Erie. In the twentieth century, there were three large chair factories, planing and grist mills, a powdered milk plant, and several furniture factories. The population was 2,934 at the 2020 census. It is part of the Erie Metropolitan Statistical Area.

Erie County is a county in the Commonwealth of Pennsylvania. It is the northernmost county in Pennsylvania. As of the 2020 census, the population was 270,876. Its county seat is Erie. The county was created in 1800 and later organized in 1803. The county is part of the Northwest Pennsylvania region of the state.