King’s Highway 17, more commonly known as Highway 17, is a provincially maintained highway and the primary route of the Trans-Canada Highway through the Canadian province of Ontario. It begins at the Manitoba boundary 50 km west of Kenora and ends south of Arnprior at the western terminus of Highway 417, 1,964.0 km to the east. This makes it Ontario’s longest highway. The highway once extended even farther to the Quebec boundary in East Hawkesbury with a peak length of about 2,180 km .
