Montcalm County is a county in the U.S. state of Michigan. As of the 2020 Census, the population was 66,614. The county is geographically located in the West Michigan region of the Lower Peninsula. The county seat is Stanton, and the largest city is Greenville. The county is named for General Marquis Louis-Joseph de Montcalm, military commander of French troops during the French and Indian War. The county was set off in 1831 and organized in 1850.