Highway 4 is the longest east–west main vehicle route on Vancouver Island, British Columbia, Canada, with a total length of 162 km (101 mi). It is known locally as the Alberni Highway to the east of Port Alberni and the Pacific Rim Highway to the west. The original highway from Parksville to Alberni and Port Alberni was completed in 1942 and was originally designated as Highway 1A. It was re-designated as Highway 4 in 1953, and was extended in 1961 to the district of Tofino, on the west coast of the Island.

Port Alberni is a city located on Vancouver Island in the province of British Columbia, Canada. The city lies within the Alberni Valley at the head of the Alberni Inlet, Vancouver Island's longest inlet. It is the location of the head offices of the Alberni-Clayoquot Regional District. Port Alberni currently has a total population of 18,259.