St. Catharines is the most populous city in Canada's Niagara Region, the eighth largest urban area in the province of Ontario. As of 2017, St. Catharines has an area of 96.13 square kilometres and 140,370 residents. It lies in Southern Ontario, 51 kilometres south of Toronto across Lake Ontario, and is 19 kilometres inland from the international boundary with the United States along the Niagara River. It is the northern entrance of the Welland Canal. Residents of St. Catharines are known as St. Catharinites.