Indiana State Route 427 is a fairly short northeast-southwest route in northeast Indiana, running from Waterloo northeast to the Ohio State line. The southwestern end is in downtown Waterloo, Indiana, at US Route 6; the town of Waterloo touches a north-south alignment that once carried the designation of US Route 27. From Waterloo, Route 427 heads northeast through Hamilton, and curves easterly to become Ohio State Route 34 at the state line. This eastern end is near Edon, Ohio.