When was the last signature placed on the US Declaration of Independence?

Answer 1

Sometimes between 1775 and 1800.

Answer 2

There is some confusion on this point. Apparently the last to sign the document was Thomas McKean. He appears to have done so a bit after the official printing of the document on January 18, 1777, perhaps even later that month.
http://en.wikipedia.org/wiki/Thomas_McKean#Continental_Congress_and_Declaration_of_Independence
http://experts.about.com/e/t/th/Thomas_McKean.htm
http://research.history.org/pf/signers/signatures.cfm

Oddly though McKean himself claims to have signed it shortly after most of the other delegates did in August 1776 (most signed it on August 2).
http://research.history.org/pf/signers/bio_mckean.cfm

If his story is true and there was a printing error, the last signature would be that of Matthew Thornton (of New Hamshire) in November 1776.
http://research.history.org/pf/signers/index.cfm


See also:
http://www.archives.gov/national-archives-experience/charters/declaration_history.html

Answer 3

1789