Gateway Transit Center is a multimodal transport hub in Portland, Oregon, United States. Owned and operated by TriMet, it comprises Gateway/Northeast 99th Avenue Transit Center, a bus transit center and light rail station serving the MAX Green and Blue Lines and eastbound Red Line trains, and Gateway North, a separate station served by westbound Red Line trains. The complex is where the three lines split, with the Blue Line proceeding east to Gresham, the Green Line proceeding south to Clackamas, and the Red Line proceeding north to Portland International Airport. It is TriMet's second-busiest transit center after Beaverton Transit Center, with 4,847 average weekday boardings for all modes in spring 2023.

When opened in 1986, it was the busiest station on the Portland–Gresham MAX line, the only line in the system at that time, and was the terminus of 11 bus lines. Currently seven bus lines serve the Gateway Transit Center.

The transit center is next to the interchange of Interstate 84 and Interstate 205, and behind a Fred Meyer store in the Gateway Shopping Center. Neighborhoods served by this station include Hazelwood, Woodland Park, Parkrose Heights, Madison South and Montavilla.

The original Gateway station includes three light rail tracks and platforms, with bus stops located on the east side of the station. The easternmost track is used by inbound (westbound) Blue and Green Line trains. Trains on this track open up doors to both the side and center platforms. The middle track is to the west of the center platform and was used by inbound Red Line trains prior to March 4th, 2024. The westernmost track has a side platform and is used by all outbound (eastbound) trains.

Prior to March 2024, inbound Red Line trains stopped at the center track because of the way the Red Line junction was configured. Because the tracks going into Gateway eastbound approach from the north, running the Red Line north to the airport from Gateway would have required the operator to change cabs. To rectify the problem, TriMet created a special configuration to the Red Line junction. Inbound, the double track line narrowed to single track about 0.5 miles (0.80 km) north of Gateway. The track runs adjacent to I-205, crosses under the main line, then swings around north on a sharp horseshoe turn, and merges with the outbound track just south of Gateway. Inbound trains then used the center track switches to cross over to the inbound track. From 2022 to 2024, as part of the Better Red project to eliminate both sections of single track on the Red Line, TriMet reconfigured the junction. Beginning on March 4th, 2024, inbound Red Line trains ascend onto a flyover bridge that crosses over the outbound track. After crossing I-84, trains stop at a side platform 500 feet (152 m) north of the original station. After making their stop, trains make a right curve, cross the inbound Blue and Green Line track, and merge with the center track before merging with the inbound track. The original loop remains in use by outbound Red Line trains.

In comparison, the Green Line's junction with the Blue Line, 0.5 miles (0.80 km) south of Gateway, is configured as a standard diverging junction.

Parking at this station and transit center was originally entirely in the form of surface lots, but in June 2006 TriMet opened a new 690-space parking garage. This compensated for the closure of the surface lot closest to the station, which was replaced by a medical building. A surface lot to the south of the station, in place since the station's opening in 1986, was not affected.

This station in the Gateway District is served by the following bus lines:

• 15 – Belmont/NW 23rd
• 19 – Woodstock/Glisan
• 22 – Parkrose
• 23 – San Rafael
• 24 – Fremont/NW 18th
• 25 – Glisan/Rockwood
• 87 – Airport Way/181st
• Columbia Gorge Express (intercity service to Multnomah Falls, Cascade Locks, and Hood River)

The station has the following features:

• Feathers: Designed by Frank Boyden, they consist of three 14–18 feet long painted aluminum feathers that work as windvanes on 20 feet poles.
• Blackberry frosted glass: The windscreens at this station (and many others) have a frosted/etched pattern of the pervasive blackberry in Oregon.

• List of TriMet transit centers

• Gateway/NE 99th Ave. Transit Center – TriMet page