History of Secondary Highway 603:
Secondary Highway 603 is a local highway in the District of Kenora that provides access from Highway 17 to the small community of Dyment, located east of Dryden. Highway 603 was first depicted on a Preliminary Route Plan prepared by the Department of Highways of Ontario (DHO) in April, 1956. The Dyment Road was designated as a Secondary Highway by an Order-in-Council dated May 9, 1956. Highway 603 has remained more or less the same ever since the route was first established in 1956. The highway is still gravel-surfaced to this day. Unless posted otherwise, the speed limit on Highway 603 is 80 km/h (50 mph). There are no services available on this highway.