State Road 431 was a state road connecting U.S. Route 31 with Interstate 465 at Exit 33. It passed through the Indianapolis suburb of Carmel, allowing traffic on U.S. 31 north of Carmel a shorter route to I-465 and the east side of Indianapolis. Until the 1990s, the SR 431 designation extended south of I-465 to 86th Street. Prior to that, it also continued south along N. Keystone Avenue to State Road 37 at Fall Creek Parkway, North Drive in Indianapolis. A second section of SR 431 followed the old route of U.S. 31 between Greenwood and the south side of Indianapolis.