31st Bombardment Squadron - Keystone LB-5. (The source for this image misidentifies the aircraft as a Keystone B-4 and is misdated to 1932, but a higher-resolution scan of the same photo clearly shows the aircraft is a specific LB-5, and another source says this aircraft was written off in 1929.)
United States Air Force
late 1920s
<a rel="nofollow" class="external free" href="http://www.minot.af.mil/shared/media/document/AFD-130307-082.pdf">http://www.minot.af.mil/shared/media/document/AFD-130307-082.pdf</a>  A Brief History of the 5th Bombardment Group, Office of History, 5th Bombardment Wing, Minot AFB, North Dakota, 2011