There are 7 US Post Offices in Caldwell County serving a total of 9,650 residents equating to 1,379 residents per post office. It's estimated that approximately 15,402 packages are handled across the 7 county post offices annually. Caldwell County is a county located in the U.S. state of Missouri. As of the 2010 census, the county's population was 9,424. Its county seat is Kingston. The county was organized December 29, 1836 and named by Alexander Doniphan to honor John Caldwell, who participated in the George Rogers Clark Native American Campaign of 1786 and was the second Lieutenant Governor of Kentucky. It was originally established as a haven for the Mormons, who had been previously driven from Jackson County in November 1833 and had been refugees in adjacent Clay County ever since. The county was one of the principal settings of the 1838 Missouri Mormon War, which led to the expulsion of all Latter-Day Saints from Missouri following the issuance of a \"extermination order\" by then Governor Lilburn Boggs. Caldwell County is part of the Kansas City, Missouri, MO-KS Metropolitan Statistical Area."