With the arrival of the auto manufacturing and the related auto parts industry after the turn of the twentieth century, Muncie's industrial and commercial development increased, along with its population growth. During World War I local manufacturers joined others around the county in converting their factories to production of war material. In the 1920s Muncie continued its rise as an automobile-manufacturing center, primarily due to its heavy industry and skilled labor force. During this time, the community also became a center of Ku Klux Klan activity. Muncie's Klan membership was estimated at 3,500 in the early 1920s. Scandals within the Klan's leadership, divisions among its members, and some violent confrontations with their opponents damaged the organization's reputation. Increasing hostility toward the Klan's political activities, beliefs, and values also divided the Muncie community, before its popularity and membership significantly declined by the end of the decade.