St. Clair Avenue has two sections. The western section extends from Moore Park in the east to Scarlett Road in the west, a distance of approximately . An eastern section picks up on the far side of the Don Valley at Taylor Creek Park, extending for to Kingston Road. Like all streets in Toronto which cross Yonge Street, St. Clair is divided into separate East and West sections, each with its own street numbers beginning at Yonge Street. Unlike most other concession-road streets in Toronto, St. Clair does not extend west into Etobicoke, due to the northern arc of Dundas Street crossing the Humber River near its western terminus, forming a link to Burnhamthorpe Road, its approximate equivalent arterial.