to nearby towns and an electric interurban system, which arrived in the early 1900s, linked it to smaller towns and larger cities, including Indianapolis and Fort Wayne, Indiana, and Dayton, Ohio. 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. Muncie residents also made it through the challenges of the Great Depression, with the Ball brothers continuing their role as major benefactors to the community by donating funds for construction of new facilities at Ball State and Ball Memorial Hospital. (The hospital, which opened in 1929, later affiliated with Indiana University Health.) The Works Progress Administration (WPA) also provided jobs such as road grading, city sewer improvements, and bridge construction. Middletown studies In the 1920s, Robert and Helen Lynd led a team of sociologists in a study of a typical middle-American community. The Lynds chose Muncie as the locale for their field research, although they never specifically identified it as "Middletown" the fictional name of the town in their study. Muncie received national attention after the publication of their book, Middletown: A Study in Contemporary American Culture (1929). The Lynds returned to Muncie to re-observe the community during the Depression, which resulted in a sequel, Middletown in Transition: A Study in Cultural Conflicts (1937). The Lynds' Middletown study, which was funded by the Rockefeler Institute of Social and Religious Research, was intended to study "the interwoven trends that are the life of a small American city." The Lynds were only the first to conduct a series of studies in Muncie. The National Science Foundation funded a third major study that resulted in two books