The Skagit River rises at Allison Pass in the Canadian Cascades of British Columbia. From there it flows northwest along the Crowsnest Highway, which follows the river into Manning Provincial Park. It turns abruptly south where it receives Snass Creek from the right, then enters Skagit Valley Provincial Park at the point where it receives the Sumallo River from the right. It receives the Klesilkwa River from the right, and turns southeast to flow into Ross Lake, where it crosses the Canada-United States border and into Washington state.