Alberta Provincial Highway No. 1, commonly referred to as Highway 1, is a major east–west highway in southern Alberta that forms the southern mainline of the Trans-Canada Highway. It runs from the British Columbia border near Lake Louise through Calgary to the Saskatchewan border east of Medicine Hat. It continues as Highway 1 into both provinces. It spans approximately 534 km (332 mi) from Alberta's border with British Columbia in the west to its border with Saskatchewan in the east. Highway 1 is designated as a core route in Canada's National Highway System and is a core part of the developing Alberta Freeway Network.

Alberta Provincial Highway No. 1A is the designation of two alternate routes off the Alberta portion of Trans-Canada Highway 1. However, it is not the only name used for spurs off Highway 1 - Highway 1X is another such designation. Despite these highways being suffixed routes of Highway 1, they are not part of the Trans-Canada Highway network, and are signed with Alberta's provincial primary highway shields instead of the Trans-Canada shields used for Highway 1.