Niagara falls/St. Catherines lies on the border but is relatively small.
(roughly 400,000 people)
Hamilton is about 45 min. down the shore and is the the closest major Urban Center. This area forms the southern end of the Grater Toronto & Hamilton Area
(roughly 8 million people)
While Fort Erie, Ontario, is directly across the river from Buffalo, Fort Erie is a town and not a city. Three Canadian cities (Port Colborne, Welland and Niagara Falls) would appear to be equidistant. Which one of them is closest would depend on the method of measurement. From downtown to downtown, the nearest Canadian city to Buffalo would be Port Colborne. However, if measured from the closest point on Buffalo's border to the closest point on a Canadian city's boundary, the winner would be Niagara Falls, Ontario.
Buffalo
The nearest Canadian city to Buffalo, New York is Fort Erie in Ontario, Canada. It is located just across the US-Canada border from Buffalo.
Halifax harbour is the closest port city to Europe
Toronto.
Windsor, Ontario is the Canadian city closest to the American border, with Detroit, Michigan lying just across the Detroit River.
Washington
Toronto
The closest Canadian city to the US border is Surrey, located in British Columbia. It is part of the Greater Vancouver area and shares a border with the US state of Washington.
Fubicktck
Buffalo (Buffalo Niagara - BUF) and Toronto (Lester B. Pearson - YYZ) are the two closest major airports to Niagara Falls. There are also regional airports nearby, in Syracuse and on Toronto Island.
The Canadian city closest to Virginia is Toronto, in Ontario, Canada. In addition, Niagara Falls is located in Toronto, Canada.