The section of Highway 575 between Acme and Carbon has had a variety of designations in its history. The 5 km (3 mi) section between Carbon and Highway 21,[1] along with a portion of present-day Highway 836, was originally designated as part of Highway 26;[4] while the 20 km (12 mi) section between Highway 21 and Acme,[1] along with present-day Highway 806, was the original alignment of Highway 21.[4] In 1958, the southern portion of Highway 21 was realigned to Highway 1 (Trans-Canada Highway) east of Strathmore, and the former section was renumbered as Highway 21A;[5][6] however, in 1962, the route was again renumbered to Highway 26.[7][8] Highway 26 was decommissioned in 1970[9][10] and in 1972, it was renumbered to its current designation.[11][12]