Indiana State Route 18 runs east-west across Southern Miami County. It runs from the Cass/Miami County Line, near Galveston, to the Miami/Grant County Line, near Mier. IN St Rt 18 passes through the following towns in Miami County. Wawapecong Converse IN St Rt 18 is multi-plexed in Miami County. Indiana State Route 19, near Converse. IN St Rt 18 intersects the following highways in Miami County. U.S. Rt. 31, near Cassville.