Originally named the
Portland Zoo Railway, the first section of track opened for service on June 7, 1958, and was formally dedicated on June 9, more than a year before the zoo opened fully at the same site. This service used the
Zooliner trainset, the railway's first and only train at that time, Meanwhile, the zoo's new West Hills site was only open on weekends, because it was still under construction, and even by August penguins and bears were the only animals moved from the old zoo, not to resume until the zoo's opening in July 1959. A fundraising campaign was launched, to raise money to build an extension – outside the zoo grounds – through the woods of Washington Park and also to build a steam locomotive. It was decided to model the planned steam engine on a real one, a
Baldwin 4-4-0 type, and construction began in the autumn, with plans to use it initially at the
Oregon Centennial Exposition, scheduled to be held the following summer in North Portland (at the site of what is now the
Portland Expo Center). The steam engine was named
"Oregon", or alternatively "the
Oregon". In the summer of 1959, the Portland Zoo Railway operated trains at two different sites. Nos. 1 and 2, the
Oregon and the
Zooliner, served a temporary railway line through the grounds of the Centennial Exposition, which lasted for about three months. The
Zooliner entered service on the exposition's opening day, June 10, along with a second train hauled by a utilitarian diesel
switcher locomotive temporarily filling in until the new steam locomotive, No. 1, was ready. The steam locomotive entered service on June 20, and it and the
streamlined Zooliner proceeded to carry passengers daily at the exposition all summer. The railroad at the zoo's then-new site in the West Hills remained closed while construction continued on the zoo itself, but reopened on the latter's opening day, July 3, 1959 (by which time most animals had been moved from the old zoo). For the next few months, the zoo line was served only by a train hauled by the locomotive that had been used during construction of that line. When the Centennial Exposition ended (on September 17, 1959), the two trains used there were moved to the new zoo line, although the steam locomotive did not enter service at the zoo until January 1960. The extension eastwards through the park to a new station near the
Rose Gardens opened on May 28, 1960. Like the two trains, the small Washington Park "Rose Garden" station building was also first used at the Centennial Exposition and was moved to the new line after the fair closed. to Washington Park Zoo. At this time, July 1, 1976 (effective date), the zoo ownership was transferred from the City of Portland (City Ordinance 143589) to the Metropolitan Service District, now called Metro. The city of Portland retained ownership of the Zoo railway, and it was leased to Metro. When the zoo was renamed again in 1998, as the Oregon Zoo, the railway was not renamed. The line also served the
Oregon Museum of Science and Industry from 1958 to 1992 while that museum was located near the zoo.
21st century A suspension of service forecast to last at least through summer 2014 was due to begin on September 23, 2013, to allow construction of a new elephant exhibit area and changes to the railway's route within and near the zoo grounds. On November 22, 2014, operations resumed on the new Zoo Loop line within the zoo. In May 2018, an online petition was created in opposition to the Washington Park Master Plan's endorsement to remove the "long route", which runs from the Oregon Zoo to the International Rose Test Garden. The master plan adopted by the city council that year called for the removal of all tracks and their replacement by a paved path. In 2025, zoo officials continued to express reluctance to study a possible reopening of the long route, saying they lacked the money needed for such a project, while the Friends of Washington Park and Zoo Railway, a non-profit organization advocating for the line's reopening, was continuing to work to generate support. The railway was listed on the
National Register of Historic Places in 2020 as a historic district using its original name, as the Portland Zoo Railway Historic District. The 1958-built
Zooliner and 1959-built
Oregon steam locomotive and their respective passenger cars were placed on the National Register, along with the railroad route itself (including the section within Washington Park), the water tank and tower, the tunnel–roundhouse complex and the Washington Park station. ==Routes==