The MAX Red Line is a light rail service in Portland, Oregon, United States, operated by TriMet as part of the MAX Light Rail system. An airport rail link, it runs from central Beaverton to Portland International Airport via Northeast Portland and Portland City Center. The Red Line serves 26 stations; it interlines with the Blue Line and partially with the Green Line from Beaverton Transit Center to Gateway/Northeast 99th Avenue Transit Center and then operates a segment through to Portland International Airport station. Service runs for 22 hours per day with a headway of 15 minutes during most of the day. The Red Line is the second-busiest service in the MAX system with an average 10,310 passengers per weekday in September 2021. Plans for an airport light rail service surfaced in the 1980s, and efforts were accelerated following Portland International Airport's rapid expansion in the 1990s. Conceived from an unsolicited proposal by engineering company Bechtel in 1997, the Airport MAX project was designed and built under a public–private partnership between a consortium of Bechtel and Trammell Crow, the Port of Portland, and local governments. Construction began in 1999, and it was completed in under two years due to the use of local and private financing and existing public right-of-way. The Red Line began operating between the airport and downtown Portland on September 10, 2001. Amid strong westside ridership on the Blue Line, Red Line service was extended west along existing tracks to Beaverton Transit Center in 2003. Track improvements and a service extension farther west to Fair Complex/Hillsboro Airport station in Hillsboro are scheduled for completion in 2024. History Background and partnership agreement In 1975, as construction of the Interstate 205 (I-205) freeway progressed north to Multnomah County, local leaders negotiated reducing the number of car lanes along a section and including a separated transit bus right-of-way; partially realized as the I-205 busway, the transit right-of-way was built but was never utilized by buses. In 1985, the Portland metropolitan area's regional government, Metro, began a study for light rail along the I-205 corridor at the behest of the Port of Portland and Clackamas County, who had wanted a line running from Portland International Airport to Clackamas Town Center and connecting with the nearly completed Portland–Gresham Metropolitan Area Express (MAX) using the I-205 busway right-of-way. Despite initially recommending the I-205 light rail line's construction by 1995, in October 1987, Metro's