The former State Road 431, now simply Keystone Avenue, remains a busy route connecting U.S. Route 31

U.S. Route 31

U.S. Route 31 is a long north–south highway connecting northern Michigan to southern Alabama, with its northern terminus at Interstate 75 near Mackinaw City, Michigan, and southern terminus at the combined U.S. Route 90 & U.S. Route 98 at Spanish Fort, Alabama...

 with Interstate 465

Interstate 465

Interstate 465 , also known as the USS Indianapolis Memorial Highway, is the beltway circling Indianapolis, Indiana, United States. It is roughly rectangular in shape and has a perimeter of approximately 53 miles . It lies almost completely within the boundaries of Marion County, except for two...

 at Exit 33. It passes through the Indianapolis

Indianapolis, Indiana

Indianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County, Indiana. As of the 2010 United States Census, the city's population is 839,489. It is by far Indiana's largest city and, as of the 2010 U.S...

 suburb of Carmel

Carmel, Indiana

Carmel is a city in Hamilton County, Indiana, United States located immediately north of Indianapolis, Indiana. The population was 79,191 at the 2010 census, and is one of the most affluent communities in the Midwest....

, 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 State Road 431 designation extended south of I-465 to 86th Street. Prior to that, it also continued south along N. Keystone Avenue to S.R. 37

Indiana State Road 37

State Road 37 in the U.S. State of Indiana is a major route in Indiana, running as a 4-lane divided highway for 110 miles of its course....

 at Fall Creek Parkway, North Drive in Indianapolis.

History

State Road 431 was officially decommissioned on October 19, 2007, with the portions north of 96th Street being turned over to the city of Carmel. Carmel Mayor James Brainard immediately proposed banning heavy trucks from the route, the Hamilton County portions of which lies within his city's corporate limits. He also pushed for a plan to build six roundabout

Roundabout

A roundabout is the name for a road junction in which traffic moves in one direction around a central island. The word dates from the early 20th century. Roundabouts are common in many countries around the world...

-style interchanges on Keystone, built 2009–2010, in lieu of widening it to at least six travel lanes throughout.

Further south in Marion County, a former southern portion of S.R. 431 extended south along Madison Avenue from the south side of Indianapolis through Greenwood. Madison Avenue, which was the original routing of U.S. 31 on Indy's south side, does not have an interchange with I-465, however. The northern terminus of this section was at Madison's intersection with East Street, which used to carry U.S. 31 to the south. The southern terminus was where Madison merges with existing U.S. 31 alignment in Johnson County

Johnson County, Indiana

As of the census of 2000, there were 115,209 people, 42,434 households, and 31,613 families residing in the county. The population density was 360 people per square mile . There were 45,095 housing units at an average density of 141 per square mile...

just south of Smith Valley Road, south of Greenwood Middle School.

Major intersections