Alberta Provincial Highway No.

21A, commonly referred to as Highway 21A, was the designation of two former spur routes of Highway 21 in Alberta, Canada.

The southern section of Highway 21A was a 33 km (21 mi) highway which started at Highway 9 in the Village of Beiseker and traveled north for 13 km (8 mi) to the Village of Acme and then turned east for 20 km (12 mi) to Highway 21, 8 km (5 mi) northeast of the Village of Carbon.

[1] It was established in 1958/59 when Highway 21 was realigned from Beiseker to Highway 1 (Trans-Canada Highway) east of Strathmore.

[7][8] The northern section of Highway 21A was a 5 km (3 mi) highway that connected Highway 21 with Highway 12 near the Hamlet of Nevis.