SR 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 portion of which lies within his city's corporate limits. At this point, the street name was changed from Keystone Avenue (a designation that remains south of the county line at 96th Street in Indianapolis) to Keystone Parkway. Brainard also pushed for a plan to build six roundabout-style ("dogbone") interchanges on Keystone, built 2009–2010, in lieu of widening it to at least six travel lanes throughout. On December 30, 2019, another such interchange was opened at the junction with 96th Street.