From Oregon City to Vancouver, the corridor is paralleled by a multi-use bicycle and pedestrian trail, as well as portions of the MAX Light Rail system between Clackamas and northeastern Portland.

The four-lane freeway travels east along Saum Creek and the Tualatin River into Clackamas County, where it passes a mix of exurban neighborhoods, forests, and farmland.

[19] The freeway travels north with tracks on the west side for the MAX Green Line, a light rail service operated by TriMet, and enters Portland in Multnomah County.

[18] From the Clackamas Town Center, the freeway travels through residential areas in Lents neighborhood at the foot of Mount Scott, home to the Willamette National Cemetery.

I-84/US 30 turns east towards the Columbia River Gorge at Northeast Fremont Street, while I-205 continues north around the suburban enclave of Maywood Park with the light rail trackway in its median.

[37] The corridor was among four Portland-area routes included in a 1955 plan from the federal Bureau of Public Roads (BPR) for what became the Interstate Highway System, which was approved one year later.

[54][55] The Laurelhurst Community Council also organized opposition to the freeway plans at public hearings the following month; local residents feared disruption of the neighborhood's character, and an influx of low-income and multi-family development.

Another alternative would remove the Lake Oswego alignment in favor of an east–west route along Division Street and Powell Boulevard (US 26) from I-5 at the Marquam Bridge, which had already been proposed for the Mount Hood Freeway.

[59][60] The Oregon State Highway Commission promised in 1963 not to pursue a Lake Oswego alignment that year because it would not be possible with opposition from the city government, but delayed its final decision by several months.

[87][88] The Portland Planning Commission responded with the 52nd Avenue alignment through Laurelhurst in lieu of wider arterial streets, and also ordered a new east–west option near the Sellwood Bridge and along Johnson Creek to avoid Lake Oswego.

[91] Facing a July 1965 deadline on the routing decision imposed by the Bureau of Public Roads, which was later extended to September, the Oregon State Highway Department turned to a new corridor that would avoid the city of Portland.

[93] The new alignment would be 3.7 miles (6.0 km) over the allocated mileage for I-205, which would require additional approval from the BPR, and had been previously proposed in March as part of the Central Clackamas Freeway.

[49] The Oregon State Highway Commission adopted the West Linn–96th alignment on November 19, 1965, and forwarded the proposal to the BPR for approval despite opposition from Washington County and residents at public hearings.

[120][121][122] The section was designated as a state scenic highway to ban billboards and commercial development near Tualatin and also included the first rest area on I-205, which was built near West Linn.

[146][147] Several business owners in eastern Portland appealed to state legislators for compensation, financial assistance for moving, and a year to relocate after freeway construction displaced them.

[154] The Portland and Multnomah County governments raised concerns about noise and air pollution near Lents School and the Rocky Butte Jail, the latter of which would sit 50 feet (15 m) from the freeway, and requested several design changes with a full environmental impact statement (EIS).

[155][156] The state's draft EIS, which was published in 1972, concluded I-205 would not have a major adverse impact on the local area but the Multnomah County environmental planner criticized it for not considering a "no build" option.

Board commissioners Donald Clark and Mel Gordon had proposed the move to force negotiations to reduce the freeway to eight lanes, remove several interchanges, add a transit corridor, and replace elevated sections with trenches.

[162] ODOT released the second draft EIS in February 1975; it concluded that constructing I-205 as originally designed would reduce congestion on other corridors but would cause increased air and noise pollution along the route, particularly in Lents and Maywood Park.

[163] In July 1975, Governor Bob Straub and Multnomah County officials announced a general compromise on a six-lane design for I-205 with seven transit stations connected by a busway, pending federal approval.

[164] At hearings, state legislators from eastern Multnomah County and members of the public criticized the design, which also reduced the number of full interchanges, as being inadequate for the area's needs.

[167] In late 1975, as a compromise between the competing proposals, ODOT engineers conceived a third design incorporating a six-lane freeway with seven interchanges that alternated between partial and full access, a separated busway, and a bicycle trail.

[36][171] The Multnomah County Board of Commissioners endorsed the third design in February 1976 and Portland City Council followed later in the month, allowing it to be included in the EIS.

[172][173][174] In June, following a positive reception for the revised design at a public hearing, the Portland City Council and Multnomah County Commissioners approved construction of I-205 by unanimous votes.

[180] Early work on the section in northeastern Vancouver was briefly interrupted following the discovery of a seasonal campsite used by Coast Salish peoples, which necessitated an archeological dig.

[196] The completion of the Glenn L. Jackson Bridge spurred major industrial and residential development in eastern Vancouver, and transformed it into a bedroom community that was characterized as urban sprawl.

It ran to the west of the freeway from Foster Road to a tunnel near Division Street, and switched to the east side through Gateway and the median from Rocky Butte to Columbia Boulevard.

[36][210] While initially envisioned for use by buses, TriMet and Metro pursued a light rail line that would connect with the existing Banfield line—now the MAX Blue Line—which opened in 1986 along the I-84 corridor.

[224] To manage congestion, ODOT installed ramp meters at 11 locations along I-205 from 1999 to 2001 and worked with Metro to study other solutions, which were deemed infeasible due to a lack of funds for substantial construction.

[232] Both projects were proposed in the 1990s, initially as a split interchange with 18th and 28th streets, amid a development moratorium on Mill Plain that the City of Vancouver imposed due to traffic congestion.