Alma is a city in Lafayette County, Missouri, and is part of the Kansas City metropolitan area within the United States. The population was 400 a…Alma is a city in Lafayette County, Missouri, and is part of the Kansas City metropolitan area within the United States. The population was 400 at the 2020 census. Alma was laid out in 1879 when the railroad was extended to that point. A post office called Alma has been in operation since 1879. The community has the name of Alma Woodson, the daughter of one of the founders.