The MAX Green Line is a light rail line serving the Portland metropolitan area in the U.S. state of Oregon. Part of TriMet's MAX Light Rail system, it connects Northeast Portland, Southeast Portland, and Clackamas, traveling and serving nine stations. It is the only MAX line that does not directly serve downtown Portland. Trains operate along the Interstate 205 (I-205) corridor between Clackamas Town Center Transit Center and Gateway Transit Center, where the line connects with the Blue and Red lines. Service operates for 21 hours on weekdays and 20 hours on weekends with headways of up to 15 minutes. It is the system's third-busiest line, averaging 11,202 weekday riders in May 2025.
Planning for light rail in Clackamas County began in the mid-1980s with one of two lines envisioned from Portland International Airport to Clackamas Town Center via the I-205 busway. Over the next decade, plans shifted from I-205 and culminated in the South/North Corridor project, which failed to secure voter-backed funding over several ballot measures. In 2001, the South/North project was partially revived with the two-phased South Corridor Transportation Project, which proposed light rail along I-205 and the Portland Transit Mall in its first phase. The I-205/Portland Mall Light Rail Project was approved in 2003, and construction began in early 2007. The transit mall segment opened on August 30, 2009, and the I-205 segment opened along with Green Line service on September 12, 2009.
On August 23, 2026, the Green Line was shortened to operate only between Gateway Transit Center and Clackamas Town Center Transit Center as part of systemwide service cuts to TriMet, making it the only MAX line that does not serve downtown Portland.
I-205 segment history Early proposals
While construction of what would become the first segment of the Metropolitan Area Express (MAX) between downtown Portland and Gresham progressed in the mid-1980s, regional government Metro unveiled plans for the Portland metropolitan area's next light rail line to serve Clackamas County. Metro proposed two routes: one between Portland International Airport and Clackamas Town Center via the I-205 freeway, and another between downtown Portland, Milwaukie, and Oregon City via McLoughlin Boulevard. A panel of local and state officials known as the Joint Policy Advisory Committee on Transportation (JPACT) endorsed the I-205 route in 1987 with a request to start preliminary engineering for light rail along this corridor in lieu of an originally planned busway. Their preferred alignment had been the I-205 busway, a partially completed, grade-separated transit right-of-way built during I-205's construction several years prior. Regional transit agency TriMet, however, wanted an extension of MAX westward to Hillsboro in Washington County to take priority for federal funding, so the agency called on local businesses and governments in Clackamas County to subsidize the proposed $88 million I-205 route.
A dispute between Washington and Clackamas county officials followed, with Clackamas County vying for additional federal assistance, including $17 million in excess funds sourced from the partially realized I-205 busway. In an effort to settle the dispute, Metro updated its regional transportation plan (RTP) in January 1989 to reassert the westside line's priority and commission preliminary work for the I-205 and McLoughlin Boulevard proposals. The U.S. Senate Committee on Appropriations approved a financing package later in September, which provided $2 million to assess the two segments, but at the behest of U.S. Senators Mark Hatfield of Oregon and Brock Adams of Washington, who were members of the committee, a segment further north to Clark County, Washington became part of the proposals.
Alignment studies initially examined extending the proposed I-205 route further north across the Columbia River to Vancouver Mall or the Clark County Fairgrounds. As the studies analyzed various alternative routes, however, support shifted to an alignment along the busier I-5 and Willamette River corridors. A route from Hazel Dell, Washington through downtown Portland to Clackamas Town Center called the "South/North Corridor" was finalized in 1994. Estimated to cost around $2.8 billion, Portland area voters approved a $475 million bond measure in November 1994 to cover Oregon's share. A Clark County vote to fund Washington's portion, which would have been sourced through sales and vehicle excise tax increases, was subsequently defeated on February 7, 1995. TriMet later sought funding for various scaled-back revisions of the South/North project following a general route between North Portland and Clackamas Town Center that voters went on to reject in 1996 and 1998. In 1997, an unsolicited proposal from engineering company Bechtel led to a public–private partnership that built an extension of MAX to Portland International Airport using the northern half of the I-205 busway from Gateway/Northeast 99th Avenue Transit Center; this extension opened in 2001 with service from the Red Line.
Revival and funding
In May 2001, JPACT revisited its plans for the I-205 and McLoughlin Boulevard corridors and the following month announced the $8.8 million South Corridor Transportation Study. By 2003, the study had narrowed down five transit alternatives including building both light rail lines, a combination of one light rail service and one improved bus service, bus rapid transit, and dedicated bus lanes. JPACT recommended both light rail options using a two-phased development plan; the I-205 line would be built by 2009, followed by a Portland–Milwaukie line via McLoughlin Boulevard five years later. The existing I-205 busway right-of-way and a potential for no new taxes were two factors that led to the selection of the I-205 corridor for the first phase. With the approval of local residents, affected jurisdictions endorsed the South Corridor Transportation Project. Plans were amended the following October to include adding light rail to the Portland Transit Mall in downtown Portland in the first phase. TriMet published the combined "I-205/Portland Mall" final environmental impact statement in November 2004 and began acquiring land in 2005.
The federal government approved the project on February 7, 2006. The combined project was budgeted at $575.7 million (equivalent to $ in dollars), of which approximately $355.7 million went to the I-205 segment. TriMet negotiated a local match of 40 percent of total funding, which amounted to $197.4 million (unadjusted). Federal funding covered the remaining 60 percent, or about $345 million, under the New Starts program. The head of the Federal Transit Administration (FTA) signed the full-funding agreement in Portland on July 3, 2007. In May 2009, the project received $32 million in federal stimulus funding from the American Recovery and Reinvestment Act of 2009, an amount already committed to the project by the federal government but made available so that TriMet could retire debt earlier. The City of Portland provided $15 million in bonds paid for by raising parking meter fees, as well as $17 million from a local improvement district and $6.3 million from systems and utilities charges. Around $36 million came from Clackamas County urban renewal funds collected from property taxes within the Clackamas Town Center urban renewal district. TriMet contributed $20.5 million, and the Portland Development Commission provided $20 million. Downtown businesses spent an additional $15.3 million to improve retail spaces along the transit mall.
Construction and opening
In February 2004, TriMet awarded the I-205 segment's design–build contract to South Corridor Constructors, a joint venture between Stacy and Witbeck, F.E. Ward Constructors—who had both worked on the Interstate MAX project—and Granite Construction Company. Construction began in February 2007. This marked the start of a 2-year closure of sections of the I-205 Bike Path; a new mixed-use path linking Clackamas County to the South Park Blocks in downtown Portland was paved as a permanent alternative. Preliminary work began in April and involved erecting light rail bridges over Johnson Creek Boulevard and Harold Street and excavating light rail underpasses below Stark and Washington streets. Crews were at work within Clackamas County by November. The line was over 70 percent complete by November 2008, with tracks laid from Gateway Transit Center to Flavel Street. To serve the expansion, TriMet ordered 22 Siemens S70 cars, which it referred to as "Type 4". Siemens delivered the first car in 2009; it made its first test run that March and entered service on August 6. The I-205 extension's first end-to-end test run, attended by local and state dignitaries, occurred that July.
The I-205 segment opened on September 12, 2009. TriMet created a new MAX service for the extension called the "Green Line", which initially ran from Clackamas Town Center Transit Center to the PSU Urban Center stations, but was later extended to the PSU South stations when those stations were infilled in September 2012. The I-205 segment added to the MAX system. Opening day festivities, paid for by sponsors and donations, were held at Clackamas Town Center and PSU, and as many as 40,000 people showed up to ride the trains, which were free that day. To address its $31 million budget deficit caused by the slow growth of payroll tax revenue amid the Great Recession, TriMet simultaneously eliminated four bus lines and implemented service cuts to 49 other routes.
Portland Mall reconstruction
A north–south rail alignment through downtown Portland had been considered as early as the 1980s. In 1991, the Portland City Council commissioned a feasibility study for a potential subway line beneath the Portland Transit Mall on 5th and 6th avenues, then served only by buses, following recommendations made by a citizen advisory committee. While planning for the South/North project in 1994, planners introduced a surface light rail alternative, which the project's steering committee later favored when they concluded that a $250 million tunnel would be too costly. Following the South/North project's cancellation, the city held off revitalization efforts for the transit mall amid proposals from local businesses to rebuild it to allow curbside parking.
In 2003, TriMet planners reconsidered adding light rail to the Portland Transit Mall after planning for the second phase of the South Corridor Transportation Study, or the Portland–Milwaukie line, revealed that a fourth service on the existing tracks in downtown's Morrison and Yamhill streets—already served by the Blue, Red, and upcoming Yellow lines—would exceed that segment's capacity. Portland business leaders likewise argued for the construction of a new bridge leading to the southern end of the transit mall instead of using the Hawthorne Bridge due to fears that the latter would create a traffic bottleneck. TriMet conducted a study proposing stations on either the left, right, or middle lanes of the transit mall and ultimately selected a hybrid center-lane travel with right-side boarding option in April 2004. A transit mall revitalization plan was approved and combined with the first-phase construction of the I-205 segment a month later. Consisting of seven stations per split on 5th and 6th avenues, the project extended the existing transit mall from 44 to 117 block faces from Union Station to PSU. It also added a continuous travel lane for private vehicles, which had not been present in the corridor's original bus-only design.