British Columbia Highway 3 is a two-lane undivided highway that becomes Alberta Highway 3 at the border in mountainous terrain, paralleling a branch of the Canadian Pacific Railway. It first crosses over to the south side of the railway and passes through the centre of Island Lake on a causeway, part of which is natural terrain. It curves through communities of the Municipality of Crowsnest Pass on the south side of Crowsnest Lake, crossing the Crowsnest River and reaching Highway 40 at Coleman. It continues alongside the railway through Blairmore, again crossing the Crowsnest River and bisecting the community of Frank and the rubble of the Frank Slide, a major landslide that killed more than 70 people in 1903. The highway, the Crowsnest River, and the railway meander east into the Municipal District of Pincher Creek No. 9 and Burmis from which Highway 507 splits south to Beaver Mines and forms an alternate route from the west into Pincher Creek. Highway 3 curves northeast to the hamlet of Lundbreck which it bypasses, and from which Highway 22 begins and runs north. The first of four former alignments of Highway 3 (all of which are now designated as Highway 3A) passes through Lundbreck, splitting from Highway 3 prior to the hamlet and rejoining it later.