Alberta Highway 4

Infobox road
state=AB
type=Hwy
route=4
length_km = 100
direction_a = North
direction_b = South
starting_terminus = Hwy 5 in Lethbridge
junction = Hwy 61 in Stirling
Hwy 52 near Stirling
ending_terminus =
cities = Lethbridge
established =
previous_type = Hwy
previous_route = 3
next_type = Hwy
next_route = 5

Highway 4 forms the most southern leg of the CANAMEX Corridor highway system in Alberta. It connects with Interstate 15 and is an important route for travellers going to and coming from the United States, connecting to cities such as Salt Lake City, Utah and Las Vegas, Nevada. Between Lethbridge and Stirling, it is also known as the Red Coat Trail (which follows Highway 61 east towards the Saskatchewan border).

Starting as an extension of Scenic Drive in Lethbridge, it travels in a southeast direction to the border crossing town of Coutts, Alberta, where it continues into Montana as Interstate 15.

Highway 4 is km to mi|100 in length. Although the entire route is a 4-lane divided highway, it does not have fully controlled access. Nonetheless, the speed limit outside of urban areas is 110 km/h (70 mph).

In September 1999, Highway 4 and Interstate 15 in Montana — being the main highway between the cities of Helena, Montana and Lethbridge — was renamed the "First Special Service Force Memorial Highway". They were chosen because they were the route taken in 1942 by the Canadian volunteers to join their American counterparts for training at Fort Harrison.