What is the primary city located on the northern shore of Lake Ontario?

The primary city located on the northern shore of Lake Ontario is Toronto. As the largest city in Canada, Toronto is situated directly on the shores of the lake, making it a significant urban center for commerce, culture, and transportation. Its geographical position on Lake Ontario not only influences the local climate but also contributes to its status as a major hub for maritime activities, tourism, and economic development.

The other cities mentioned—Montreal, Vancouver, and Ottawa—are located elsewhere in Canada. Montreal is found along the St. Lawrence River, while Vancouver lies on the Pacific coast, and Ottawa is located upstream on the Ottawa River. None of these cities are positioned along the northern shore of Lake Ontario, which differentiates Toronto's unique and significant role in the region.