The Whirlpool Rapids Bridge, commonly called the Whirlpool Bridge, and until 1937, known as the Lower Steel Arch Bridge, is a spandrel braced, riveted, two-hinged arch bridge. It crosses the international border between Canada and the United States, connecting the commercial downtown districts of Niagara Falls, Ontario and Niagara Falls, New York. This bridge is located approximately 1.5 kilometres (0.9 mi) north of the Rainbow Bridge and about 2 kilometres (1.2 mi) from the Falls. This bridge was acquired by the Niagara Falls Bridge Commission in January 1959.
The bridge was designed by Leffert L. Buck and constructed between April 9, 1896, and August 27, 1897. It was constructed around the Niagara Falls Suspension Bridge so as not to interrupt daily traffic.
The bridge has two decks. The upper deck carries the railway traffic while the lower deck is a roadway reserved for passenger vehicles only; commercial vehicles and pedestrians are prohibited. The Whirlpool Bridge is reserved for NEXUS members, a joint program implemented by the Canada Border Services Agency (CBSA) and United States Customs and Border Protection (CBP). There is one lane of traffic to the United States and one lane to Canada. The American side connects to New York State Route 104 and New York State Route 182, while the Canadian side connects to the historic terminus of King's Highways 3A, 20 and 8, now known as River Road and Bridge Street.
A single set of train tracks crosses over the bridge. The Via Rail Niagara Falls Station is located on the Canadian side of the bridge in Niagara Falls, Ontario and a new Amtrak Niagara Falls Station is under construction located on the American side of the bridge in Niagara Falls, New York.
Just upstream is the disused Michigan Central Railway Bridge, which was used to carry rail traffic.
Amtrak took over maintenance responsibility of the rail deck from Canadian National (CN) in late 2012. Currently the Maple Leaf train service, jointly operated by Amtrak and Via Rail, is the only train to use the bridge; CN routes freight over the International Railway Bridge at Fort Erie, Ontario–Buffalo, New York instead. In November 2009, the bridge began extensive refurbishment; repairing and replacing the catwalk and some of the steel beams and rivets, sandblasting, and a paint job were among the major maintenance tasks undertaken.