The 56-page document was purchased by a private collector, according to Sotheby's spokeswoman Lauren Gioia. It had been expected to fetch only $50,000 to $70,000.
The census covered the population of the nation's 13 states and Southwest Territory, breaking it down by state and county.
The state population is listed according to five categories: free white males 16 years and upward, free white males under 16, free white females, all other free persons and slaves. The county breakdown is the same, but starts with free white males 21 years old instead of 16.
Jefferson was secretary of state at the time. His signature certified that the information was an official accurate count.
"Probably as few as 200 were printed," said Selby Kiffer, Sotheby's books and manuscripts specialist. "They were distributed to the members of the House and Senate and to the state governments. In that sense it was very much an official governmental document and not a public document."
The first census was a "straightforward headcount" that did not include the amount of land or animals owned, Kiffer said. Unlike census data collected today, it is not a measure of socio-economic standards.
The 1791 census lists the population for New York City and county — Manhattan and the South Bronx — as 33,131. The population for Westchester County, now considered the suburbs of New York City, is listed as 24,003. The Washington, D.C., area, with some districts unreported, had 35,691 people.
Only two other 1791 first edition copies signed by Jefferson have come up at auction since 1975. One sold in 2004 at Christie's New York for $85,000; the other sold at Sotheby's in 2000 for $47,500.
The Jefferson-signed census is part of a large collection of handwritten letters, documents and other manuscripts of American history that is part of the James S. Copley Library. Copley, a newspaper publisher, was editor of the San Diego Union-Tribune and CEO of Copley Press.