Curtiss XP-40 Warhawk tested in the NACA wind tunnel, Langley Research Center, Virginia, 1939.
I edited together videos from United States Army Air Corps/Forces (USAAC/USAAF) newsreels, released in 1941. Curtiss P-40 Warhawk:
Before the U.S. entered the Second World War, ‘volunteers’ were being paid by the U.S. government to fly P-40 ‘Flying Tigers’ for China, against the Japanese. However, after Japan bombed Pearl Harbor the Flying Tigers became an official USAAC/USAAF unit, along with some of their pilots being transferred to the Navy/Marine Corps, and the Chinese began flying their own P-40s. Here is a poor quality, silent film of Chinese operated P-40s:
Here are some photos of various versions of P-40s throughout the war:
P-40 tied down on Iceland, 23SEP1941.
P-40E being tested by NACA, 20MAY1942.
A U.S. taxpayer funded P-40F is presented to a French air force chaplain in Algiers, northern Africa, 1942.
Warhawk lands at Burg-el-Arab, Egypt, October 1942.
Somewhere in the Caribbean, December 1942.
25DEC1942, “…SSGT J.A. Muller, CPL John W. Coleman, and CPL L.B. Thomas of the 16th Fighter Squadron, 51st Fighter Group, consume their Christmas dinner on the field at a base somewhere in China.”
May 1943, Dobodura, New Guinea.
A bullet riddled British Royal Air Force P-40 ‘Kittyhawk’ somewhere in northern Africa, 1943.
Port Moresby Air Depot, Papua, New Guinea. A P-40 converted into a two seat observation plane, sometime in 1943.
Sometime in 1943, Burma-India Theater of Operations.
Sometime in 1943, Abadan, Iran, Soviet pilots play chess before flying their U.S. taxpayer funded P40s to the Karelian Front.
P-40 lands on a new airfield on Baker Island (aka New Nantucket), 11SEP1943.
Apamama Island, Gilbert Islands, January 1944.
February 1944, Upper Assam, India.
A Curtiss C-46 lands while a Curtiss P-40K watches, somewhere in China, sometime in 1945.
Chinese anti-air spotters are taught not to shoot down a Warhawk, sometime between 1945 and 1946.
Final flight outta the U.S.?: 
Yankee Lady, the last take-off? Does anybody know what is going on?