The new riding of Markham-Unionville consists of part of the former riding of Markham-Unionville and a part of the former riding of Oak Ridges-Markham. The southern boundary of the riding is 407 ETR, and it extends to just north of 19th Avenue. Highway 404 is its western boundary, and its eastern boundary is Highway 48 from north of 19th Avenue to 16th Avenue. Between Highway 48 and McCowan Road the riding is boarded on the south by 16th Avenue. From 16th Avenue down to the southern boundary it is bordered by McCowan Road.
Population of Markham-Unionville: 104 693
Electoral Population of Markham-Unionville: 81 583
Area of Markham-Unionville: 89 Sq. KM