Welcome BACK to Alaska
To arrive in Skagway, one must leave the Anchorage area, travel to Tok, Alaska, then enter the Yukon and travel south to Whitehorse, then west into Skagway. So one clears Canadian customs to exit Alaska, then must clear U.S. customs to enter Alaska again, then Canadian customs again when exiting Alaska, then U.S. customs when entering the lower 48.