The Declaration of Independence which is housed in the National Archives building here is actually a copy done by Thomas Jefferson.  The original was lost or destroyed.

A declaration of independence is an assertion of the independence of an aspiring state or states. Such places are usually declared from part or all of the territory of another nation or failed nation, or are breakaway territories from within the larger state. Not all declarations of independence are successful and result in independence for these regions.

• http://en.wikipedia.org/wiki/Declaration of independence