Record keepers realised the file was missing from the US National Archive in 2000, The Washington Post reported. Other important missing documents include the patent for Eli Whitney's cotton gin as well as hand-written letters from Abraham Lincoln and photos from the moon.
But volunteer archivist Bob Beebe tracked down the file last month, hidden among 15ft-high (5 metre) stacks of documents in a limestone special records storage cave in Lenexa near Kansas City, meaning the Wright Brothers parent was misfiled rather than completely lost or stolen.
In 2012, the US' National Archives was hit by a rash of robberies, with priceless items presumed stolen by Barry Landau, a conman who had amassed the largest collections of stolen American artifacts ever.
Landau managed to steal more than 10,000 historical items by impersonating a presidential historian. His collection included the original reading copy of Franklin D. Roosevelt's famous 1937 inaugural address as well as documents signed by George Washington, Thomas Jefferson, Voltaire, Mark Twain, and Charles Dickens.
In 2012, a former Archives emplyee was arrested for stealing nearly 5,000 items, including one of the original news recordings chronicling the Hindenburg disaster.