[4] Union Township is in southern Crawford County, bordered to the northeast by French Creek and to the south by Conneaut Outlet, which flows through Conneaut Marsh and joins French Creek at the southeast corner of the township.

Interstate 79 crosses the township, with the closest access being Exit 141 (Pennsylvania Route 285 to Geneva) to the south and Exit 147 (U.S. Route 6 and 322 to Meadville) to the north.

[4] As of the census[6] of 2000, there were 1,049 people, 412 households, and 294 families residing in the township.

There were 454 housing units at an average density of 28.7 per square mile (11.1/km2).

23.8% of all households were made up of individuals, and 9.2% had someone living alone who was 65 years of age or older.