U.S. Federal Route 421 is a north-south highway in North-Central White County. It runs from the White/Pulaski County Line, near Monon, to Reynolds. At Reynolds, it runs east-west to Monticello. In Monticello, it runs north-south and enters Carroll County, near Patton. U.S. Rt. 421 passes through the following towns in White County. Monon
U.S. Rt. 421 is multi-plexed in White County. U.S. Rt. 24, from Reynolds to Monticello.