Jefferson County Missouri is located south of St. Louis County with the Meramec River being part of the boundary between the two counties. Ste. Genevieve and St. Francois counties lie to the south and Franklin and Washington counties lie to the west. Jefferson County was formed in 1818 along with much of the other surrounding counties. It covers 664 square miles and has 15 large communities within its boundaries. In 2010, the US Census put the population of Jefferson County at 218,733. The county seat is located in the city of Hillsboro.
Below is a list of the cities in Jefferson County. Click on any of the links to find that community's specific government information such as the address to the city hall, phone numbers of the mayor, city clerk, police department and other information.