State highway in northern Ohio, US
State Route 603 (SR 603) is a north–south state highway in the northern portion of the U.S. state of Ohio. Its southern terminus is at State Route 95 near Perrysville, and its northern terminus is at State Routes 61 and 98 in Plymouth along the Baseline Road that separates Huron County and Richland County, and subsequently the southern boundary of the Firelands and Connecticut Western Reserve.