CANISTOTA, S.D. — It’s a common site in Old Order Amish communities: blue dresses, black pants and white socks on a clothesline billowing in a brisk, early spring wind. But this clothesline and its contents aren’t in Pennsylvania or Ohio or Iowa. They are behind a motel in the small south­eastern South Dakota town of Canistota. The clothes’ owners are among the vanloads of Amish who travel from as far as Delaware and New York to Canistota for treatments at the renowned Ortman Chiropractic Clinic.