Asked by @AvatarSage on Twitter.
$1,000 bills exist! Until 1949, the U.S. government printed $500, $1,000, $5,000, and $10,000 bills.
In 1969, the Department of the Treasury and the Federal Reserve System announced these large denomination bills would be discontinued due to lack of use.
$500, $1,000, $5,000, and $10,000 bills are legal tender and may be found in circulation according to the Bureau of Engraving and Printing. Most are probably in the hands of private dealers and collectors.
The largest bill ever printed was the $100,000 Gold Certificate in 1934 and 1935, but it was not circulated. It was only used for transactions between Federal Reserve Banks.
View photos of the large denominations, including the $100,000 Gold Certificate.