There are 5 US Post Offices in Warren County serving a total of 6,275 residents equating to 1,255 residents per post office. It's estimated that approximately 10,016 packages are handled across the 5 county post offices annually. Warren County lies in western Indiana between the Illinois state line and the Wabash River in the United States. According to the 2010 census, the population was 8,508. The county seat is Williamsport. Before the arrival of non-indigenous settlers in the early 19th century, the area was inhabited by several Native American tribes. The county was officially established in 1827 and was the 55th county to be formed in Indiana. It is one of the most rural counties in the state, with the third-smallest population and the lowest population density at about 23 inhabitants per square mile (8.9/km2). The county has four incorporated towns with a total population of about 3,100, as well as many small unincorporated communities. The county is divided into 12 townships which provide local services. Much of the land in the county is given over to agriculture, especially on the open prairie in the northern and western parts; the county's farmland is among the most productive in the state. Nearer the river along the southeastern border, the land has many hills, valleys, and tributary streams and is more heavily wooded. Agriculture, manufacturing, government, education, and health care each provide substantial portions of the jobs in the county. Four Indiana state roads cross the county, as do two U.S. Routes and one major railroad line."