A patron asked us about a very unusual quotation the other day: apparently someone, sometime said that Thomas Jefferson was "...a mean-spirited, low-lived fellow, the son of a half-breed Indian squaw, sired by a Virginia mulatto father..."; this was supposedly a comment made by Jefferson's political opponents in the election of 1800. But who actually said this? One of my neighbors in grad school once gushed that librarians were "like wolverines, man! I mean, you ask them a question and they just WON'T LET GO until they answer it!" He wasn't kidding. In hopes that somebody will find this enlightening, useful, or even just entertaining, here's how I ran this particular question down and killed it.

1. Checked contemporary full-text sources for pamphlets, newspaper articles, etc. that might have contained such a claim: Early American Imprints I (nothing); Early American Imprints II (zippo); America's Historical Newspapers (nichts); 19th Century American Newspapers (dud); American Broadsides and Ephemera (whole lot of nothing). (I searched for both of the phrases, "half-breed Indian squaw" and "virginia mulatto father" in each database.)
2. Searched for the entire phrase on Google. It's all over the Internet, of course, uncited. No help there. I narrowed the search down to Google Books, only, and found the quotation used in a small selection of secondary sources on dirty election campaigns. Some of them even have footnotes, but Google won't show them to me. Curses.
3. I started searching for only portions of the entire quotation. This yielded slightly different results. One of them was a book that Google only showed me part of (and it was the wrong part, even), but this isn't the Jefferson Library for nothing! We have the book in the stacks. It mentions this quotation appearing in something called the Jonnycake Papers. Hmmm.
4. I googled "Jonnycake Papers" and found nothing useful. Just to cover all the angles, I googled "Johnnycake Papers" too, and got lots of sites chastising people for spelling "Jonnycake Papers" wrong. Okay then. I searched for these fabled "Jonnycake Papers" on WorldCat and found NOTHING.
5. I sat around for a day or so thinking about this.
6. I googled another portion of the original quotation in question, just to see what came up. Lo, I got "The Jonny-Cake Papers" on Google Books! (Silly hyphen!) These Jonny-Cake Papers are so old (1915) that Google showed me the whole thing, and there on page 232 was my reference. I still have no clue what it is, though.
7. I turned my attention to finding out more about the Jonny-Cake Papers, and right off the bat found an article on JSTOR from the Journal of American Folklore from 1945 all about the Jonny-Cake Papers. (I LOVE the Internet sometimes!) It turns out the J-CP's were a rambling collection of local oral history and tall tales from Narragansett, Rhode Island. Back to our original question, the narrator seems to be recalling (not to say hyperbolizing) the election campaign of 1800. Since it seems highly unlikely to me that the narrator could be recalling, verbatim, a printed comment about Thomas Jefferson, I'm fairly convinced that this is the source of our quotation.
8. Just for fun, I looked for the quotation again on the Internet to see where it's appearing. Unfortunately it seems some sites are taking it as legitimate information about Thomas Jefferson's parentage. Oh dear.

My attempt to set everybody straight is on our encyclopedia here.