Union County -- -- which is on the upper part of Butler County's western border -- was one of four new counties formed by the Indiana legislature of 1820-21, according to George Pence and Nellie C. Armstrong in Indiana Boundaries: Territory, State and County (1933). It was named Union County because it was a union of land taken from three counties. "Wayne, Fayette and Franklin all contributed to the small new county of Union," effective Jan. 5, 1821," said Pence and Armstrong. "Franklin County lost territory to both Fayette and Union, in spite of numerous spirited protests against reduction below the constitutional area of 400 square miles." The Ohio-Indiana border forms Union County's eastern boundary with Franklin County on the south, Fayette County on the west and Wayne County on the north.
A commission selected Brownsville as county seat in 1822 report. A new commission named Liberty the county seat in 1823. With 161.5 square miles, it is one of Indiana's smallest counties. Estimated population in 2003 was 7,238. Near the southeast corner of Union Twp. is West College Corner, which adjoins College Corner, Ohio. The Ohio portion of College Corner is both Butler and Preble counties. (See College Corner)
Other communities in Union County are Contreras, Charlottesville, Cottage Grove, Lotus, Billingsville, Egypt Hollow, Roseburgh, Dunlapsville, Salem, Goodwins Center, Kitchel, Witts Station, Clifton, Yankeetown and Philomath. Union Township on the southeast corner borders on Butler County, Ohio. It includes West College Corner, Charlottesville, Contreras, Salem and Billingsville.