The Whirlpool Rapids Bridge, also known as the Lower Steel Arch Bridge, is an internationally-renowned bridge that connects the downtown areas of Niagara Falls, Ontario, and Niagara Falls, New York. It is situated about 1.5 kilometers north of the Rainbow Bridge and roughly 2 kilometers from the Falls. This spandrel-braced, riveted, two-hinged arch bridge is historically significant, having been constructed in the late 1800s. It replaced the outdated Niagara Falls Suspension Bridge, which had been in use since 1855.

Civil engineer Leffert L. Buck designed the new bridge, selecting the arch design as it was more cost-effective than the suspension bridge. He built the new bridge around and below the old one, which allowed train and pedestrian traffic to continue without interruption. The final pieces of the Suspension Bridge were dismantled on August 27, 1897, leaving the Lower Steel Arch Bridge to stand in its place.

Over the years, several railway companies, including the New York Central Railroad, Great Western Railway, Erie Railroad, Canadian National Railway, and Amtrak, have used the bridge. Currently, only the Maple Leaf train service, jointly operated by Amtrak and Via Rail, uses the bridge. The lower deck is reserved for passenger vehicles only, and commercial vehicles and pedestrians are prohibited. The bridge may only be used by members of the NEXUS trusted traveller program, jointly operated by the Canada Border Services Agency (CBSA) and the United States Customs and Border Protection (CBP).

The Bridge is situated immediately upstream of the Michigan Central Railway Bridge, which has been out of service since 2001. The bridge has two decks, with the upper deck carrying railway traffic and the lower deck serving as a roadway. Vehicles entering Canada must pay a $5.00 USD toll electronically using an account linked to their E-ZPass transponder or NEXUS card. There is one lane of traffic to the United States and one lane to Canada, with two inspection lanes at each end for traffic entering the respective countries.

Although pedestrians and bicycles are not allowed on the bridge, tourists can still appreciate its beauty from afar. Traffic is heaviest between May and September, with Friday being the most congested day of the week. There are numerous overhead road signs that will alert drivers to bridge delays and other road conditions. Depending on how far you are from the bridge, conditions can change substantially when you get there.

The Whirlpool Rapids Bridge is an important historical landmark that has played a vital role in connecting the downtown areas of Niagara Falls, Ontario, and Niagara Falls, New York. While tourists cannot walk or bike across the bridge, they can appreciate its beauty from a distance. The bridge is also a vital part of the transportation infrastructure in the region, with many trains passing over it and passenger vehicles using the lower deck to cross the Niagara River.