I have been doing some research on early United States history for a project, and I keep running into various treaties signed between the colonies/United States and Native American tribes. Where would these treaties actually be kept after they were signed? And, if different, where are they kept now?
I'm not qualified to answer this question from a historical perspective, but in modern times it's the function of the National Archives and Records Administration (NARA) to store and preserve the "official" versions all acts of Congress, executive orders, federal regulations, etc., and to make them available to the public.
According to their website, the original treaties between the United States and the Native American tribes are currently housed at the National Archives in Washington, D.C.