It consists of the South and North Channel Bridges that originally opened in 1958, and spans the St. Lawrence Seaway.

Previously known as the Cornwall-Massena International Bridge, the SIBC was a private bridge whose outstanding stock was purchased by the Saint Lawrence Seaway Authority (Canada) and the Saint Lawrence Seaway Development Corporation (U.S.) in 1957.

In 2000, the international border crossing that the Seaway International Bridge comprises was named the Three Nations Crossing, in recognition that it connects the Akwesasne Mohawk Territory, a self-governing nation, to the United States and Canada.

It was named in 2000, in honor of the Mohawk of Akwesasne, a federally recognized tribe in the United States and First Nation in Canada.

Their reserve extends across the international border, in addition to that between Quebec and Ontario.