Comment by emilyfm

You can drive a further 1200km+ road distance north of Whitehorse, Yukon on the Dempster Highway to Inuvik in the Northwest Territories.

End of the road appears to be just north of town: https://goo.gl/maps/shD9UoxTtK42

Western Canada is big. If you drive from Inuvik to San Diego over 60% of the entire road distance is within Canada.