At Japan’s military defeat in 1945, the Japanese military disposed of Gaihozu on a large scale since the maps contained highly sensitive information. However, between the end of the war in September 1945 until early 1946, a group of scholars who feared that Gaihozu would be scattered and lost rescued some thousands of Gaihozu, saved the maps, and sent them to Tohoku University.
The rest of Gaihozu became the target of confiscation by the occupation forces, particularly U.S. Army Map Service (AMS), which was a map-making organization established in response to the military demand for maps of Pacific Theater. In preparation for the approaching Cold War, AMS focused on collecting maps of Japan and China after 1944, and the Korean Peninsula, Manchuria, and Siberia after the end of World War II. Surplus map copies were eventually transferred to the Library Congress via the Depository Program and finally distributed to the universities all over the United States. Several U.S. universities currently hold Gaihozu collections. Many of these institutions received their copies through AMS’s college depository program. 
 Azusa Tanaka and Shigeru Kobayashi, "Gaihozu, Maps of the Areas Outside the Japanese Territory Prepared by the Former Japanese Army, in the Libraries in the United States: Discovery and Processing." (Manuscript submitted for publication, 2018), 1.
Read more stories about the UW's Gaihozu collection featured on Jackson School of International Studies East Asia Center News:
Treasures from the East Asia Library; Gaihozu Maps (MARCH 6, 2017)
More Gaihozu Acquired by East Asia Library (OCTOBER 12, 2018)
Gaihozu maps at UW Libraries were found by chance in 2014 when Map Collection Librarian, Matt Parsons, was moving the Seattle Times’ subject files from the Map Collection to the Microform & Newspaper Collections. One of Matt's student assistants, a native Japanese speaker, recognized the value of this Gaihozu collection and brought it to the attention of Japanese Studies Librarian, Azusa Tanaka. The maps were added to UW's collection through either the Library of Congress or the Army Map Service between 1954 and 1979. However, there are no official records in the UW Libraries concerning the provenance or acquisition of the University of Washington’s Gaihozu collection.
In Summer 2018, Oregon State University Libraries generously donated their Gaihozu collection to the UW Libraries.
Some of the Gaihozu in the UW collection were captured at the Imperial Japanese Navy’s Yokosuka Naval District (Yokosuka Chinjufu (横須賀鎮守府)), at the East Asian Research Institute (Toa Kenkyusho (東亜研究所)), and at the Imperial Japanese Army’s Narashino Training School (Rikugun Narashino Gakko (陸軍習志野学校)), rather than at the Land Survey Department of Imperial Japanese Army. Many of the maps in UW's Gaihozu collection were used by multiple owners and include handwritten notes from previous owners, including personal names and map notes.
Beginning in 1944, former Oregon State College (now Oregon State University) Library Director William H. Carlson maintained a correspondence with U.S. Army Map Service staff to discuss the library's acquisition of over 50,000 captured maps. Correspondence between 1944 and 1947 reflects the scope of the U.S. Army Map Service's college depository program.