Aerial view of East Portland, Oregon, east side of the Portland yard to the west, and the Steel Bridge, January 1950, from the Oregon Historical Society Collection.

Portland Zoo Train 4-4-0 steam locomotive at Portland, Oregon, on June 16, 1990. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, park attraction.

Portland Zoo Train 4-4-0 steam locomotive at Portland, Oregon, on June 16, 1990. Photo by J.M. Fredrickson. Other Subject Classes: steam locomotive, park attraction.

Portland Zoo Train 4-4-0 steam locomotive with passenger cars at Portland, Oregon, on June 16, 1990. Other Subject Classes: steam locomotive, passenger cars, park attraction.

Boy Scouts pose with the Portland Zoo Aerotrain at the Portland Zoo station in Portland, Oregon. Photo by J.M. Fredrickson. Other Subject Classes: park railroad.

Boy Scouts pose in front of the Portland Zoo train at the Zoo station. Photo by J.M. Fredrickson. Other Subject Classes: park railroad.

Portland Zoo Railway 4-4-0 steam locomotive on loan to the 1959 Oregon Centennial Exposition held at North Portland in 1959. Photograph by Alden Raney. Other subject classes: Train-Miniature.

Portland Zoo Railway 4-4-0 steam locomotive on loan to the 1959 Oregon Centennial Exposition held at North Portland in 1959. Photograph by Alden Raney. Other subject classes: Train-Miniature.

Portland Zoo Railway 4-4-0 steam locomotive on loan to the 1959 Oregon Centennial Exposition held at North Portland in 1959. Photograph by Alden Raney. Other subject classes: Train-Miniature.

Portland Zoo Railway 4-4-0 steam locomotive on loan to the 1959 Oregon Centennial Exposition held at North Portland. Repairs being done on front truck in 1959. Photograph by Alden Raney. Other subject classes: Train-Miniature.