The original MAX route followed a diverse combination of rights-of-way, including on-street running through downtown Portland and the Lloyd District, separated trackage alongside Interstate 84, the center median of East Burnside Street (itself an old trolley right-of-way), and parts of an old Portland Traction Company interurban line.

MAX came about as the result of popular opposition to the proposed Mount Hood Expressway, connecting Portland and Gresham through southeast Portland. The route would have cut a wide swathe through several eastside neighborhoods. Instead, the funds proposed for the highway project were applied to the construction of the east side light rail corridor. Construction began in 1981; it took about five years to construct the line.

These original cars were delivered using another old interurban route, the East Portland Traction's Springwater Line between southeast Portland and Ruby Junction.

For most of its first 12 years, MAX operated on a weekday schedule of 15-minute headways during off-peak hours and 10-minute headways during rush hour. Reduced schedules were offered on weekends and holidays.

Most trains operated with two cars, with some early and late off-peak services using single cars (the two-car length of MAX trains was, and remains, dictated by the length of street blocks in downtown Portland, which do not allow longer train lengths without blocking intersections.)

The agency also re-used sections of the old Oregon Electric interurban railway line between downtown Beaverton and downtown Hillsboro. Rail transit service returned to the two cities for the first time since 1933.

The first portion of the line, from downtown to SW Salmon in the Goose Hollow neighborhood, opened on Aug. 31, 1997. Delays in the construction of the Washington Park tunnels, caused primarily by slow going through some of the underground rock layers, kept TriMet from opening the line as far as 185th Avenue in Beaverton, as originally planned. 

The body shells for this fleet were built in Germany, but final assembly took place at a Siemens plant in Sacramento, Calif. The cars were delivered to TriMet on railway flatcars and dropped off at an unloading ramp connecting the Westside line with a Portland & Western railroad spur between the Beaverton Creek and Merlo Road stations.

The inauguration of west side service and the new low-floor cars also coincided with service increases and improvements along the entire route. A "bridge plate" that extended from the car side when the doors open allowed the cars to handle wheelchairs, strollers and bicycles. It eliminated the need for the hydraulic wheelchair lifts, and speeded up station stops considerably.

The added equipment also provided enough rolling stock to run two-car trains at all times. It significantly increased capacity during the September 1997 closure of one span of the I-5 Interstate Bridge for lift mechanism repairs -- a closure that greatly increased ridership on the east side, particularly from the Gateway Transit Center.

TriMet and municipalities along the proposed route subsequently produced a modified alignment that would have connected the Clackamas Town Center and the Kenton neighborhood in north Portland.

Certain parts of this alignment, including trackage through downtown Milwaukie and Portland, generated significant controversy. Funding measures went to voters throughout Oregon in 1996 and in the Portland metro area in 1998, losing in close votes each time.

Despite these defeats at the polls, TriMet continued to project an alignment between northern Clackamas County and Clark County, Wash. The latest modification to this routing, announced March 16, 1999, extended light rail north from the Rose Quarter Transit Center to the Multnomah County Expo Center along the Columbia River.

The Metro council, the City of Portland and the TriMet board all subsequently approved the project. Construction began Feb. 19, 2001. Twenty-seven additional Siemens SD660 low-floor cars, numbered in the 300 series, increased the light rail fleet in anticipation of this service. These began arriving at the Ruby Junction shops in February 2003 and entering revenue service in September 2003 after initial testing. The line opened May 1, 2004.

The line opened Sept. 10, 2001, serving stations along the I-205 corridor north of Gateway and in the industrial and commercial core east of the airport. It terminates at the south end of the main terminal building, adjacent to Concourse A. TriMet purchased six SD600 cars to increase the fleet for this service. 

Clark County, Wash. and Clackamas County have recently taken a fresh look at light rail, so TriMet planners began discussions on up to four possible extensions, two into Clackamas County and two into Vancouver, Wash:

• From Gateway Transit Center south to Clackamas Town Center, following the I-205 alignment.
• From downtown Portland to Milwaukie, crossing the Willamette River and following an alignment along the Union Pacific railroad tracks and McLoughlin Boulevard.
• From the Portland Expo Center north across the Columbia River into Vancouver, then north-northeast to Vancouver Mall, following I-5 and State Highway 500. This would extend the Interstate Avenue alignment.
• From Gateway Transit Center north to Vancouver Mall following the I-205 alignment. This would tie in with the existing airport line.

TriMet and local government officials announced Feb. 17, 2003 that they had selected a plan to construct both the I-205 and Milwaukie alignments. The I-205 route would come first, opening in 2009, with the Milwaukie route following about four years later.

The project includes new trackage in downtown Portland, using the Transit Mall on SW 5th and 6th Avenues. This would serve both the Union Station area and the Portland State University campus. Construction began in January 2007, and the line is scheduled to open in September 2009.

Siemens will build 21 new S70 low-floor light rail cars to increase the TriMet fleet for the new service. The first cars are expected to arrive sometime in late 2008. The S70 series is currently operating in several other U.S. cities, including Houston, Texas; San Diego, Calif.; and Charlotte, N.C.

MAX stations have become the focus of commercial, corporate and residential expansion around them. Whole developments, such as Orenco Station in Hillsboro, the Round in Beaverton and the Civic Neighborhood in Gresham, provide a mix of these uses right alongside the tracks.

The stations also have some of the most distinctive artwork found throughout metropolitan Portland. The Washington Park station, for example, includes murals and rock tubes that outline the millions of years of geological development in the Tualatin Hills.

TriMet introduced a new identification system for its existing and future MAX services in late 2000. The Gresham-Hillsboro route is the Blue Line; the Airport route is the Red Line; and the Interstate route is the Yellow Line. The Green Line is the designation for the route now under construction from Portland into Clackamas County along the I-205 corridor.

Station signs and kiosks, and destination signs on the trains are all color coded; On the Blue and Red line trains, destination signs appear in white on a background showing the route color. Yellow Line destination signs appear with the names in black on a yellow background.

TriMet also introduced a new logo and color scheme in 2002. The new scheme eliminated the narrow horizontal brown, orange and red stripes, replacing them with broader blue and yellow-gold striping. The new 300-series light rail cars arrived in the new colors, and TriMet has repainted several 100-series cars in the new scheme as part of regular overhauls.

TriMet, working with the governments of suburban Washington County and Clackamas County, has also moved ahead with plans for the 14.7-mile commuter rail line between Beaverton and Wilsonville, projected to open in October 2008. This service will use existing rail lines operated by the Portland & Western Railroad.

A new stretch of track along Lombard Street in downtown Beaverton will allow direct access into the Beaverton Transit Center and provide cross-platform connections with MAX trains and TriMet buses. Colorado Railcar, Inc. has built a small fleet of diesel-powered railcars and trailer coaches for this service. Construction on this route began in October 2007.

Blue Line trains operate on the following schedules, current as of September 2007:

Weekdays:

• Approximately every 20-30 minutes before 5 am and after 10 pm.
• Approximately every 15-20 minutes between 5 am and 6 pm.
• Approximately every 5-15 minutes between 6 am and 6 pm.
• Approximately every 15-20 minutes between 6 pm and 10 pm.

Saturdays:

• Approximately every 20-30 minutes before 6 am.
• Approximately every 10-15 minutes between 6:00 am and 6 pm.
• Approximately every 15-20 minutes between 6 pm and 10 pm.
• Approximately every 30 minutes after 10 pm.

Sundays/Holidays:

• Approximately every 15 minutes between 4 am and 10 pm.
• Approximately every 30 minutes 10 pm.

The first and last trains of the day are as follows:

From Gresham:

• Monday-Thursday: -- First train at 4:05 am, last train at 11:31 pm.
• Friday: First train at 4:05 am, last train at 12:32 am.
• Saturday: First train at 4:27 am, last train at 12:32 am.
• Sunday: First train at 5:40 am, last train at 10:33 pm.

From Hillsboro:

• Monday-Thursday: First train at 4:07 am, last train at 11:32 pm.
• Friday: First train at 4:07 am, last train at 12:30 am.
• Saturday: First train at 4:38 am, last train at 12:32 am.
• Sunday: First train at 5:32 am, last train at 10:32 pm.

Blue Line trains originating in Hillsboro in the early morning and terminating there in the late evening enter or go out of service at the Elmonica (Beaverton) yard. These trains also make all stops between there and downtown Hillsboro westbound in the morning and eastbound in the evening. Some early morning Hillsboro-bound trains originate at E. 197th Ave./Ruby Junction.

From Beaverton Transit Center:

• Monday-Friday: -- First train at 3:37 am, last train at 10:22 pm.
• Saturday: First train at 3:37 am, last train at 10:22 pm.
• Sunday and Holidays: First train at 3:37 am, last train at 10:22 pm.

From Portland International Airport:

• Monday-Friday: First train at 4:55 am, last train at 11:56 pm.
• Saturday: First train at 4:56 am, last train at 11:56 pm.
• Sunday and Holidays: First train at 4:57 am, last train at 11:37 pm

Early morning Red Line trains originate at the Elmonica (Beaverton) yard and terminate there in the late evening. These trains also stop at all stations between there and Beaverton Transit Center.

Yellow Line trains operate approximately every 15 minutes and take about 30 minutes to run between Downtown Portland and the Expo Center.

The first and last trains of the day are as follows:

From Downtown Portland:

• Monday-Friday: -- First train at 5:08 am, last train at 12:35 am.
• Saturday: First train at 5:41 am, last train at 12:33 am.
• Sunday and Holidays: First train at 5:40 am, last train at 11:32 pm.

From Expo Center:

• Monday-Friday: First train at 4:50 am, last train at 12:02 am.
• Saturday: First train at 4:51 am, last train at 12:49 am.
• Sunday and Holidays: First train at 4:51 am, last train at 10:56 pm

Early morning Yellow Line trains originate at the Ruby Junction (Gresham) yard and late evening trains terminate there. These trains also stop at all stations between Ruby Junction and Rose Quarter, where they enter or depart Interstate Avenue.

MAX stations include Transit Centers with connections to TriMet bus routes (shown as TC); those with park-and-ride lots or parking garages (shown as PR); those with connections to the downtown Portland transit mall (shown as TM); and those connecting with the Portland Streetcar loop (shown as PS).

There are also Quick Drop sites for travelers to or from Portland International Airport. These are stations along the Red Line where travelers and their baggage can get dropped off or picked up at or near the train platforms. These are designated by the letters QD.

Stations located on the downtown Portland one-way couplets (SW Morrison and Yamhill and SW 5th and 6th) are designated as westbound (WB) or eastbound (EB). Beginning in September 2008, MAX services at Beaverton TC will connect with Westside Express Service (WES) commuter trains.

The current standard fare for MAX trains is $1.75 for travel in one or two zones and $2.05 for travel through all three zones. All-day tickets and reduced-rate fares for children, senior citizens and riders with special needs are available, as are weekly, monthly, half-month and annual passes. Ticket machines are located on all station platforms. An area between the Lloyd Center and the Portland downtown core is designated as Fareless Square, and MAX riders riding within this area do not pay a fare.

TriMet's light rail maintenance shops and car storage yards are located on SE 199th Avenue in Gresham (Ruby Junction) and on SW Jenkins Road in Beaverton (Elmonica).