U.S. Federal Route 421 is a north-south highway in a north-south highway in Carroll County. It runs from the White/Carroll County Line, south of Monticello, to the Carroll/Clinton County Line, near Rossville. It runs in the western part of the county. U.S. Rt. 421 passes through the following towns in Carroll County. Patton Yeoman Delphi
Radnor Ockley Owasco U.S. Rt. 421 is multi-plexed in Carroll County. Indiana State Route 39, throughout Carroll County. Indiana State Route 18, from near Springboro to near Delphi.
A BGS on NB IN St Rt 25. A BGS on NB IN St Rt 25. A guide marker at the end of the ramp from NB IN St Rt 25. NB U.S. Rt. 421/IN St Rt 39; WB IN St Rt 18 at IN St Rt 25. NB U.S. Rt. 421/IN St Rt 39; WB IN St Rt 18 at Ripley Park. SB U.S. Rt. 421/IN St Rt 39; EB IN St Rt 18 east of Market St.
