It begins in Coutts at Alberta's busiest border crossing, winding north through gentle rolling hills and farmlands in the south of the province.

It bypasses Milk River, Warner and Stirling before reaching Lethbridge where it becomes 43 Street and ends at Crowsnest Trail on the east side of the city.

The highway began as a trail parallel to a branch of the Canadian Pacific Railway that was built in the late 1800s connecting Lethbridge to Great Falls.

Paving and a realignment to eliminate curves was completed by 1947, and in the late 1980s Alberta Transportation announced plans to twin the entire length as part of upgrades to the CANAMEX Corridor south of Calgary that included Highways 2 and 3.

New pavement was built east of Stirling to allow the divided highway to curve smoothly to the northeast, and a portion of the former two lane road remains.

[15][16] The route was identified as a key corridor connecting Alberta to major cities of the United States for the purposes of trade and tourist travel.

From its northern end in Lethbridge, it originally followed the railway line on a southeasterly heading before turning due east along Township Road 54 at New Dayton.

[9] It then followed present-day Highway 36 south through Warner, before turning back east toward the railway north of Milk River, before following it through the town and into Coutts.

[21] Along with other Lethbridge officials, they hoped the highway would be given priority over other projects in the area as the Coutts border crossing was far and away the busiest in Alberta, carrying more traffic than all the others combined.

[22] Work began in 1945 to reconstruct and straighten out the existing alignment of the highway that consisted of the numerous aforementioned 90° turns.

[30] Ordinarily, Alberta begins to consider upgrading to a divided highway when traffic levels reach 10,000 vehicles per day.

[34] By 1996, work had begun on a 13 km (8.1 mi) section north of Coutts, and a $26 million commitment had been made by Alberta to a group of projects that included the widening of Highway 4 in Lethbridge.

[40][41] The route was travelled between 1942 and 1944 by Canadian volunteers of the force to join their American counterparts for training at Fort William Henry Harrison near Helena in preparation for World War II.

[42][43] Several Canadian and American members of the force that came to be known as the "Devil's Brigade" were on hand in Milk River for the dedication of plaques for the route, and signs at both ends of the highway were erected.

In combination with proposed bypasses of Fort Macleod, Claresholm and Nanton, the project would eliminate all traffic lights on the CANAMEX Corridor in southern Alberta.