Blairstown is a village in Henry County, Missouri, United States. The population was 97 at the 2010 census. A post office, and a firearms s…Blairstown is a village in Henry County, Missouri, United States. The population was 97 at the 2010 census. A post office, and a firearms store are located there. Blairstown got its start when the railroad was extended to that point. A post office called Blairstown has been in operation since 1886. The city was named after railroad magnate John Insley Blair.