Markham is a city in the York Region of Ontario, Canada. It is approximately 30 km northeast of Downtown Toronto. In the 2021 Census, Markham had a population of 338,503, which ranked it the largest in York Region, fourth largest in the Greater Toronto Area, and 16th largest in Canada. The city gained its name from the first Lieutenant-Governor of Upper Canada, John Graves Simcoe, who named the area after his friend, William Markham, the Archbishop of York from 1776 to 1807.