Physical Characteristics. Union County is in Northeast Florida, north of Gainesville, and is bordered by Baker, Bradford, Alachua, and Columbia counties. The county has 245.76 square miles of land and 4.0 square miles of water for a total of 249.76 square miles. The average January temperature is 55.9 degrees fahrenheit, and the average August temperature is 81.4 degrees fahrenheit. The average annual rainfall is 49.40 inches.
History. The smallest county in the state, Union County was established from a portion of Bradford County in 1921. The county was to be named New River, the original name of Bradford County. The source of the name Union is unclear, although it has been suggested that Union was derived from the fact that both parts of Bradford County were united in desiring a separation.
