Amite County, Mississippi is located in the south-western portion of the state. Amite County was formed from Wilkinson County on 24 February 1809 while Mississippi was still a territory. It was named after the Amite River which is located in the county. The name Amite is derived from the French amitié, meaning "friendship" and was used in commemoration of their friendly treatment by the Houma Indians.
The old boundary line, as established by the Choctaw treaty of 1801, runs a few miles west of its original eastern boundary line. At the time of its establishment, it contained a population of about 1,500. Subsequently, from parts of its eastern area were formed the counties of Pike, Marion, Perry, Greene, and Lamar. In 1870 part of its territory was given to, in part, form Lincoln County.
The county seat is Liberty, where the local center of justice held its first court session in 1809. Liberty was incorporated in 1828. Construction on the current Amite County courthouse (the oldest in the state of Mississippi) was began in 1839. This courthouse replaced the original courthouse that had been built in 1812. The first Chief Justice was Micajah Davis and the first sheriff of the county was David Lea. The first Circuit Court Judge was Francis Xavier Martin who later became the Chief Justice of the Louisiana Supreme Court.
Gail Borden, of Borden Milk fame, conducted condensed milk experiments in Liberty. Dr. Tichenor's world-known antiseptic originated in Liberty. Liberty is also the site of Mississippi's first Confederate Memorial, completed and dedicated in 1871.
Amite county has a total area of 731 square miles, of which 729 square miles is land and 2 square miles (0.28%) is water. The population recorded in the 1810 Federal Census was 4,750. The 2010 census recorded 13,131 residents in the county.
Neighboring counties and parishes are Franklin County (north), Lincoln County (northeast), Pike County (east), Tangipahoa Parish, LA (southeast), St. Helena Parish, LA (south), East Feliciana Parish, LA (southwest), and Wilkinson County (west).
Communities in the county include Centreville (mostly in Wilkinson County), Crosby (partly in Wilkinson County), Gloster, Liberty, Coles, Gillsburg, and Smithdale.