The Metropolitan Area Express (MAX) is a light rail system serving the Portland metropolitan area in the U.S. state of Oregon. Owned and operated by TriMet, it consists of five lines connecting the six sections of Portland; the communities of Beaverton, Clackamas, Gresham, Hillsboro, Milwaukie, and Oak Grove; and Portland International Airport to Portland City Center. Trains run seven days a week with headways of between 30 minutes off-peak and three minutes during rush hours. In 2019, MAX had an average daily ridership of 120,900, or 38.8 million annually. Due to the COVID-19 pandemic, which impacted public transit use globally, annual ridership plummeted, with only 14.8 million riders recorded in 2021.
MAX was among the first second-generation American light rail systems to be built, conceived from freeway revolts that took place in the 1970s. Planning for the network's inaugural eastside segment, then referred to as the Banfield Light Rail Project, started in 1973 ahead of the cancelation of the Mount Hood Freeway. Construction began in 1982, and service commenced between downtown Portland and Gresham on September 5, 1986. The original 27-station, 15.1-mile (24 km) line has since been expanded to 94 stations and 59.7 miles (96.1 km) of track. The latest extension, from Portland to Milwaukie, opened in 2015.
MAX is one of three urban rail transit services operating in the Portland metropolitan area, the other two being the Portland Streetcar and WES Commuter Rail. MAX directly connects with them as well as with other transit services such as Amtrak, Frequent Express, and local and intercity buses. Trains operate with two-car consists due to downtown Portland's short city blocks. Vehicles and platforms are fully accessible, and fares are collected through the Hop Fastpass payment system.