The river originates on the eastern slopes of the Canadian Rockies, in the Sawback Range inside Banff National Park, and then flows east through the mountains and foothills region. It turns north-east before Sundre and keeps this heading to the city of Red Deer, where it turns east, and then south before Stettler. It flows south with its valley protected by provincial and regional parks such as Tolman Badlands Heritage Rangeland, Dry Island Buffalo Jump Provincial Park, Dry Island Corridor and Midland Provincial Park. At Drumheller it has a south-east direction, and while it flows through Dinosaur Provincial Park it turns east and flows to the Alberta/Saskatchewan border, which it crosses at Empress. It flows for 16 km through Saskatchewan before it merges into the South Saskatchewan River.