The 1945 Japan–Washington flight was a record-breaking air voyage made by three specially modified Boeing B-29 Superfortresses on September 18–19, 1945, from the northern Japanese island of Hokkaidō to Chicago in the Midwestern United States, continuing to Washington, D.C. The flight was made by three United States Army Air Forces (USAAF) generals and other airmen returning to the United States from their overseas duty after World War II. At that date, it involved the heaviest load carried by an American aircraft, the longest nonstop flight made by the USAAF, and the first nonstop flight from Japan to the United States made with a complete aircraft. However the flight did not break the then-world distance record established by the Royal Air Force in 1938. It's worth noting that the Martin PB2M was rated at 144,000 lb much earlier. Also, the tests of the B-29 under the leadership of E.H. Rowley in June, 1945 with Grand Slam bombs may have been run at similar loads.

The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Flying Fortress, the Superfortress was designed for high-altitude strategic bombing, but also excelled in low-altitude night incendiary bombing, and in dropping naval mines to blockade Japan. B-29s dropped the atomic bombs on Hiroshima and Nagasaki, the only aircraft ever to drop nuclear weapons in combat.