The bridge was part of the unprecedented period of bridge building in Portland during the 1920s. It was opened on December 21, 1926, and cost $1.9 million to construct. The bridge was designed by famed engineer Gustav Lindenthal.
The bridge is named for its location close to Ross Island, an island in the Willamette River which measures about one-and-a-half by one miles. The bridge is about 800 feet (250 m) north of the island and does not connect with, nor does it provide access to, Ross Island. There is a pedestrian walkway on the north side of the bridge, with no barrier between the sidewalk and the westbound right lane.
The bridge's girders were originally painted black, but in 1955–56 they were repainted green. In 1961, Portland architect Lewis Crutcher suggested repainting all of Portland's downtown-area bridges from black into different colors, and the proposal also included changing the Ross Island Bridge's color to blue. The proposal was approved by the Multnomah County Commission, and repainting of the Ross Island Bridge was carried out in the summer of 1965. The bridge's color remains blue today, specifically "phthalo blue".
In 1976, ownership was transferred from Multnomah County to the Oregon Department of Transportation. In 2000–2001 the bridge underwent a $12.5 million renovation in which the deck was replaced, the railings were replaced and upgraded, and the drainage system and lighting were improved. During this renovation, lead paint was discovered, causing some delays and cost overruns.
The bridge with 99E in the foreground near the interchange
At the east end of the bridge, US 26 becomes Powell Boulevard as it passes over Oregon Route 99E (Pacific Highway East). Route 99E is a high-speed arterial road, built to near-freeway standards; just to the north it passes over a railroad on the twin Martin Luther King, Jr. Viaduct and Grand Avenue Viaduct. There is a direct ramp from US 26 east to Route 99E south, but no northbound access. Likewise, there is access from Route 99E north to the bridge (via Woodward Street and 8th Avenue), but traffic from Route 99E south must exit at Mill Street, about 1/2 mile (1 km) to the north, and head down Division Street, 11th Avenue and Milwaukie Avenue to US 26. This same movement is done to reach US 26 east; US 26 west however has direct access to Route 99E north via 9th Avenue and Woodward Street. A fourth direct ramp runs from Route 99E north to US 26 east.
The pedestrian walkway simply becomes the north sidewalk of Powell Boulevard, a major street.