The FAA is amending four high altitude Area Navigation (RNAV) Q-routes (Q-140, Q-818, Q-935, and Q-947) that cross the United States (U.S.)/Canada border in the north central U.S. This action updates the latitude/longitude coordinates for three Canadian waypoints listed in the Q-route descriptions contained in the FAA aeronautical database to match the Canadian aeronautical database source information.