Apparently, at the last minute, Thomas Jefferson changed a word in the Declaration of Independence. Today, we call ourselves citizens, not subjects.
According to this article in the Washington Post, the Library of Congress used spectral analysis to figure out that Jefferson made this change in word choice while the ink on the paper was not yet dry.
Here is a description of the process they used. And here is the Library of Congress press release.
Citizens, not subjects--that has made all the difference. Happy Independence Day!