Hangar 701 (Building 5715)

Built: 1941

Location: 7000 NE Airport Way at Portland International Airport

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Background: The Portland Army Air Base was officially established in 1941, just a few months before the attack on Pearl Harbor, prompting the United States to enter World War II. To make the base operational, the United States Army Corps of Engineers (USACE) quickly built military facilities on the site. The base would eventually include more than 100 different buildings. Hangar 701 was constructed in 1941 to serve as an aircraft maintenance space for the Portland Army Air Base both during and after World War II. The U.S. Air Force Reserve acquired Hangar 701 when it occupied the west end of the Portland Air Base. The building's ownership was transferred from the Air National Guard to the Port of Portland in 1985-1986 (Collins 2005). Horizon Air leased the building from the Port of Portland in the late 1980s and used the building and several other buildings nearby as their maintenance facilities. Once a modern facility was constructed in 1998, Horizon Air moved most of its operations out of Hangar 701 (Hill 1998) but used the hangar until about 2000. The hangar was demolished in 2007 due to disrepair and safety concerns.

Architectural significance: Hangar 701 was recommended to be eligible for listing in the National Register of Historic Places, for its statewide significance within the themes of World War II, military aviation, and industry; and for its rarity in Oregon as a type of aircraft hangar that was built on the first Oregon airbase developed specifically for World War II aviation. Although Hangar 701 generally conformed to the 1941 Army Air Corps Technical School Type Two-Unit hangar design, which was widely built nationwide during the war buildup, it appeared to be the only one of its type constructed and remaining in Oregon.

The period of significance was 1941 to 1945, when Hangar 701 functioned as an aircraft maintenance hangar during World War II associated with the U.S. Army Air Corps (USAAC) during its most significant period of development. The USAAC was re-designated by the War Department as the U.S. Army Air Force (USAAF) in June 1941. The hangar achieved its primary significance during the period it was associated with the USAAF.

Hangar 701 functioned as a maintenance hangar for the Portland Air Base and housed office and shop activities along its north and south ends. The structure was most likely constructed from standardized plans developed by the Army Air Corps Construction Division and then implemented with possible modifications by the USACE. Hangar 701 was a two-unit hangar, which means it could house two aircraft that could be serviced from both the west and east ends through large sliding doors. The steel structure measured 162 feet wide, 202 feet long and 45 ft high at the peak of the roof, making it one of the largest structures on the base. The roof was supported by a low-pitched, combination Howe and Pratt truss system. The roof was decked with wood planking.

Multiple-pane clerestory windows were positioned along the uppermost portion of the north and south walls among the trusses, allowing light into the hangar bays. Along the interior of the central hangar bay on the north and south sides were wooden walkways supported by steel brackets. Steps at either end of both walkways allowed access to the second-floor offices, workspaces, and classrooms. The interior walls dividing the main hangar bay from the flanking workspaces were composed of 2x4-inch (in) stud framing between the steel framing columns. They were sheathed on the hangar side with horizontally- oriented, corrugated steel siding. The sides facing the workspaces were clad in horizontally-oriented 1x6- in tongue-and-groove planking.

The general character of the historic setting of the hangar was impacted by modern buildings to the north and to the southeast. Two one-story buildings, one dating from circa 1942, and the other dating from circa 1962, were sited in front (north) of the hangar facing the PDX runway system. Directly southeast of Hangar 701, the Port of Portland constructed a massive Ground Run-up Enclosure (GRE) in 2001 to reduce noise associated with post-repair jet engine run-ups. The Portland Air National Guard Base is also located southeast of the hangar. To the west of the hangar are modern transport facilities operated by the United Parcel Service. Most of the buildings that were associated with World War II within the immediate area have been demolished. Many other buildings were constructed to support the hangar, including a circa-1942 boiler building that provided steam heat for the hangar and a circa-1942 “night lighting” electrical control building that was used for military airfield operations.

On Memorial Day 1948, the levee west of Vanport, Oregon, was breached, flooding and destroying the entire city of Vanport, displacing thousands of residents and killing 15 people. Flood waters continued to rise, and on June 11th, after several levee failures on the Columbia River, floodwaters reached Hangar 701 and its associated buildings. The rest of the Army Air Base and the Portland International Airport flooded as well. However, Hangar 701and the supporting buildings withstood the floods and remained in use until the 21st century.