The Steel Bridge is a through truss, double lift bridge across the Willamette River in Portland, Oregon. Its lower deck carries railroad and bicycle/pedestrian traffic, while the upper deck carries road traffic and light rail (MAX), making the bridge one of the most multimodal in the world. It is the only double-deck bridge with independent lifts in the world and the second oldest vertical-lift bridge in North America, after the nearby Hawthorne Bridge. The bridge links the Rose Quarter and Lloyd District in the east to Old Town Chinatown neighborhood in the west.

The bridge was completed in 1912 and replaced the Steel Bridge that was built in 1888 as a double-deck swing-span bridge. The 1888 structure was the first railroad bridge across the Willamette River in Portland. Its name originated because steel, instead of wrought iron, was used in its construction, very unusual for the time. When the current Steel Bridge opened, it was simply given its predecessor's name.

The structure was built by Union Pacific Railroad and the Oregon Railway and Navigation Company at a cost of $1.7 million. It opened in July 1912 to rail traffic and on August 9, 1912 to automobiles. Between 1984 and 1986 the bridge underwent a $10 million rehabilitation, including construction of the MAX light rail line.

In 2001, a 220-foot long and 8-foot wide cantilevered walkway was installed on the southern side of the bridge's lower deck as part of the East bank Esplanade construction, raising to three the number of publicly accessible walkways across the bridge, including the two narrow sidewalks on the upper deck.