The route is generally rural and straight, passing near several communities within the Regional Municipality of York.

The route is 65.2 kilometres (40.5 mi) long and travels through the municipalities of Markham, Whitchurch-Stouffville, East Gwillimbury, Georgina, and Brock.

[3][4] Beginning at Major Mackenzie Drive (York Regional Road 25), the route progresses northward from the rural–urban fringe of the Greater Toronto Area into farmland.

A future extension of Donald Cousens Parkway will bypass former Highway 48 (Main Street) through downtown Markham in 2018 just north of Major Mackenzie.

Just south of Sutton, the route curves east, meeting York Regional Road 9 (High Street), which travels into the town.

The final section travels eastward to Highway 12, south of Beaverton and west of Cannington and Woodville.

However, the east–west section that lies to the south of Lake Simcoe is slightly developed and features a lower speed limit of 60 km/h (37 mph).

Markham Road began as the eighth concession east of Yonge Street in the Home District of Upper Canada, and was blazed by settlers to whom land had been granted along the right-of-way.

[5][6] Improvements to the road and the necessary funds were authorized by an act of the Upper Canada provincial parliament on February 13, 1833 for the section in Scarborough township between Danforth Road (present day Painted Post Drive) and the Eighth Concession at the border with Markham township.

[8] On July 28 of that year, the parliament of the Province of Canada passed an act to establish the Scarborough and Markham Plank-road Company, which was authorized to further improve the road surface to macadamized or planked construction between Kingston Road in Scarborough and Markham Village in the north, and further north and then east to Stouffville along the Markham-Stouffville township line,[8] a line then formed between today's Stouffville Road and Main Street Stouffville.