In 1980, Alberta starting twinning Highway 1 and Highway 16, expecting the process to take 10 years. The last part of the highway in Alberta to be twinned was inside Banff National Park, which was under federal government jurisdiction.
The original trans-Canada route between Calgary and BC was via Highway 93 between Banff and Radium through Kootenay National Park. Work began in 1910 on the "Auto Route of the Great Divide", to build a highway across the Rocky Mountains, starting with a road from Banff to Castle Junction to Banff. Interrupted by World War I, the road between Castle Junction and Windermere was completed between 1920 and 1922, and officially opened in 1923 at the Banff Windermere Highway.
In 1946, following World War II, Prime Minister Mackenzie King changed the name of Castle Mountain to Mount Eisenhower to honour the World War II general Dwight D. Eisenhower. At that time, Castle Junction was renamed Eisenhower Junction. Castle Mountain was officially restored to its original name in 1979, at which time Eisenhower Junction was also renamed Castle Junction, though many locals still use the old name.
In 1933 the construction began on a highway between Jasper and Banff, and was completed in 1939, and officially opened in 1940.
In 1965 the Canmore route is realigned away from the town centre, and the old route designated Highway 1A.
Icefields Parkway photos
Parks Canada Agency commenced twinning of the highway in 1979, balancing transportation service levels, public safety, while mitigating adverse effects on wildlife mortality and habitat fragmentation. This let to the construction of above ground "animal bridges" as well as underpasses.
The first section was from the Park Gates to Banff in 1981, and to Sunshine Village including an overpass to the ski resort, completed by 1983.
Next to be twinned was the 14km segment between Moraine Creek and Castle Junction, including new highway alignment and nine major crossing structures, including two 60m wide landscaped overpasses, page wire fencing to prevent wildlife from accessing the highway.
Lastly was the 35 km stretch between Castle Junction and the B.C. border was completed in 2014. The 82 kilometres of project cost various stakeholders about $317M. Exclusion fencing on both sides of the highway has reduced wildlife-vehicle collisions by over 80 percent.