Formed April 1, 1820 (68th county)
Union County (62,790), Marysville (25,586)
The red brick courthouse was built in 1883. It is located on Main Street between 5th and 6th streets. Ohio State Highway 38 passes one block east of the location. David W. Gibbs provided the Renaissance designs for the courthouse. A Justice Center was added in 2001. The courthouse features a tower with a working clock. The grounds have veteran memorials. There have been four courthouses in Marysville, two of which were built in 1822 and 1838. The county was formed on April 1, 1820 as the 68th county with Milford Center as the county seat. Marysville became the county seat in 1821. The county was taken from Franklin, Delaware, Madison, and Logan counties and thus its name. Marysville is named for the daughter of the founder, Mary Culbertson.
Union County government consists of an auditor, a sheriff, an attorney, and a coroner (executive). It has 3 Commissioners (legislative.) Three Common Pleas Court Judges and a court clerk serve Union County (judicial.) The county is in central Ohio. Columbus, Ohio is directly southeast and Toledo, Ohio is north of the county. The county center is 6 miles North of Marysville nearer Peoria. The county is surrounded clockwise by Marion, Delaware, Franklin, Madison, Champaign, Logan, and Hardin counties.
The area of the county is 436.7 square miles. It is 45 out of 88 in the state. It ranks 49 out of 88 in population in the state. It has a density of 143.8 persons per square mile making it 35 out of 88 in the state. Union County has 54.4% of its population in its incorporated areas. United States Highway 33 goes northwest to southeast in the county from Logan County to Franklin County. United States Highway 36 crosses east to west from Delaware County to Champaign County. United States Highway 42 cuts the southeast corner from Delaware County, east, to Madison County, south. Union County looks like a capital letter L. Marysville is located in the southern quarter of the county. Marysville is the county seat and the largest city. It is 40.8% of the county population. This county is in the Columbus Metropolitan Statistical Area.
Magnetic Springs
Marysville
Milford Center
Richwood
Unionville Center
Dublin
Plain City