Marthasville is a city in Warren County, Missouri, United States. The population was 1,136 at the 2010 census. The Katy Trail, a 240-mile long bike path, passes through Marthasville. The original graves of Daniel Boone and his wife were located near there. In 1845, Boone's remains were disinterred and moved to Kentucky for burial. Resentment in Missouri about the disinterment grew over the years, and a legend arose that Boone's remains never left Missouri.