Many supporters of the legalization of marijuana often mistakenly say that the Declaration of Independence is written on hemp but they are only partially correct.
The original drafts of The Declaration of Independence were written on paper material made from Hemp which is, yes, the same plant as marijuana.
The majority of paper at the time was made from a combination of hemp and flax as well as the occasional use of a verity of recycled cloth fibers.
The final document which is housed in the National Archives was treated as any other important historical document at the time and indeed even to day would be. After the final product was approved (which happened to be on hemp paper) it was then transferred to a fine Vellum parchment made of sheepskin which was the practice for any significant document for well over a millennium.