.svg) Highway 3 | ||||
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| Crowsnest Highway | ||||
 Major highways of southern Alberta with Highway 3 highlighted in red | ||||
| Route information | ||||
| Maintained by the Ministry of Transportation and Economic Corridors | ||||
| Length | 324.11 km[2] (201.39 mi) | |||
| Existed | October 8, 1917[1]–present | |||
| Major junctions | ||||
| West end |  Highway 3 at B.C. border in Crowsnest Pass | |||
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| East end |   Highway 1 / Highway 41A in Medicine Hat | |||
| Location | ||||
| Country | Canada | |||
| Province | Alberta | |||
| Specialized and rural municipalities | ||||
| Major cities | ||||
| Towns | ||||
| Villages | ||||
| Highway system | ||||
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Highway 3 (officially named the Crowsnest Highway) is a 324-kilometre (201 mi) highway that traverses southern Alberta, Canada, running from the Crowsnest Pass through Lethbridge to the Trans-Canada Highway in Medicine Hat. Together with British Columbia Highway 3 which begins in Hope, it forms an interprovincial route that serves as an alternate to the Trans-Canada from the Lower Mainland to the Canadian Prairies.
Highway 3 begins as a two-lane continuation of BC Highway 3 in the Canadian Rockies at Crowsnest Pass, winding through the foothills to a junction with Highway 2 west of Fort Macleod. Briefly concurrent with Highway 2, it becomes a divided highway and part of Alberta's "Export Highway", a segment of the CANAMEX Corridor that stretches from Alaska to Mexico. In Lethbridge it is an expressway named Crowsnest Trail that crosses the Oldman River and meets the northern termini of Highways 4 and 5; the former is a major route that assumes the designation of the Export Highway, connecting to Interstate 15 in Montana, while the latter branches southwest to Magrath and Cardston. Leaving Lethbridge, Highway 3 passes through Coaldale and Taber before reverting to a two-lane highway that ends at Highway 1 in Medicine Hat.
For its entire length, Highway 3 follows the alignment of the Canadian Pacific Railway. It was first a rough dirt road known as the Red Trail plotted in the early 1900s. Later numbered as Highway No. 3, it was designated as a southern branch of the former Trans-Canada Highway by the 1920s and improved to gravel then eventually paved, widened with shoulders, and upgraded to an expressway in sections. The Trans-Canada was officially routed through Calgary in the 1960s, but Highway 3 remained an important alternate route to the west coast and was incorporated into the National Highway System in 1988. Twinning of the first segment between Lethbridge and Coaldale had been completed by the mid-1960s, and it was officially named the Crowsnest Highway in the late 1970s. A major expressway realignment along Crowsnest Trail in central Lethbridge was completed in the 1980s, and twinning of the Fort Macleod–Lethbridge segment was completed in the mid-1990s.
Alberta Transportation has long-term plans to upgrade the entire route to a freeway; the work will include twinning west of Fort Macleod and east of Taber, and an eventual elimination of at-grade intersections. Plans have been drafted for a free-flowing bypass of Lethbridge that will realign Highways 3 and 4 to the north and east of the city respectively, and a future Fort Macleod bypass will realign Highway 3 to the south of the town connecting to a newly extended Highway 2. A $150 million project announced in 2021 will twin the highway from Taber to Burdett, with work tentatively planned to begin 2024.