Ontario Highway 4

King's Highway 4, also known as Highway 4, is a provincial highway in Ontario, Canada. It starts at Highway 3 in Southwold. It then continues northward until ending at Highway 8 in Clinton. It is 100.8 kilometers (62.6 miles) long. The highway passes through Elgin County, Middlesex County, and Huron County. It also passes through the major cities of St. Thomas and London.

Highway 4
Location of Highway 4 in Southern Ontario      Current route      Former route
Route information
Maintained by Ministry of Transportation of Ontario
Length	100.8 km (62.6 mi)
Existed	February 26, 1920–present
Major junctions
South end	Highway 3 – St. Thomas
Major intersections	Highway 401  Highway 402  Highway 7
North end	Highway 8 – Clinton
Location
Country	Canada
Province	Ontario
Major cities	St. Thomas, London
Towns	Exeter, Clinton
Highway system
Ontario provincial highways Current Former 400-series
← Highway 3 Highway 5 →
Former provincial highways ←  Highway 3B   Highway 4A  →