As part of establishing the corridor in northeastern Alberta, two secondary highways (662 and 664), along with Highway 28X and a portion of Highway 46 were renumbered to Highway 55 in , matching Saskatchewan Highway 55, while the original route east of Edmonton became part of Highway 21. Highway 55 was paved throughout the 1980s.
To create a corridor in northeastern Alberta, two secondary highways (662 and 664), along with Highway 28X and a portion of Highway 46 were renumbered to Highway 55, aligning with Saskatchewan Highway 55, while the original route east of Edmonton became part of Highway 21. Highway 55 was paved throughout the 1980s.