Highway 21 is a cross-border spur in the Regional District of Central Kootenay in British Columbia. First opened in 1964, the highway travels 14 km (9 mi) northwest along the Kootenay River from its connection with Idaho State Highway 1 at the Rykerts Canada-U.S. border crossing to a point on the Crowsnest Highway (Highway 3) just 1 km (about ½ mi) west of Creston.

Highway 21
Creston-Rykerts Highway
Route information
Maintained by British Columbia Ministry of Transportation and Infrastructure
Length	14.12 km[1] (8.77 mi)
Existed	1964–present
Tourist routes	Part of the International Selkirk Loop
Major junctions
South end	SH-1 in Rykerts / Porthill
North end	Hwy 3 near Creston
Location
Country	Canada
Province	British Columbia
Highway system
British Columbia provincial highways
← Hwy 20 → Hwy 22

Approximately 4 km (2 mi) from its northbound terminus, Highway 21 comes to an intersection with Erickson Street as it enters Creston. At this point, motorists intending to travel eastbound on the Crowsnest Highway toward Cranbrook and the Alberta border can bypass Creston's main business district and connect to the Crowsnest at Erickson. Westbound motorists can continue on Highway 21 to its northern terminus.^[2]