Richmond Hill is a city in south-central York Region, Ontario, Canada. Part of the Greater Toronto Area, it is the York Region's third most populous municipality and the 27th most populous municipality in Canada. Richmond Hill is situated between the cities of Markham and Vaughan, north of Thornhill, and south of Aurora. Richmond Hill has seen significant population growth since the 1990s. It became a city in 2019 after being a town since 1957.