Maysville is a city in DeKalb County, Missouri, United States. The population was 1,095 at the 2020 census. Maysville is the county sea…Maysville is a city in DeKalb County, Missouri, United States. The population was 1,095 at the 2020 census. Maysville is the county seat of DeKalb County. Maysville is part of the St. Joseph, MO–KS Metropolitan Statistical Area.