i believe they used to make $1000 bills but they were recalled (or whatever u call it). doesn't make sense as these days there's probably people who carry that much money on them & don't want a bulgy wallet (too bad i'm not one of them!).
Yeah they used to make larger denominations but now the $100 bill is the largest.
From the Department of the Treasury:
"Currency notes of denominations above $100 are not available from the Department of the Treasury, the Federal Reserve System, or the Bureau of Engraving and Printing. On July 14, 1969, the Department of the Treasury and the Federal Reserve System announced that currency notes in denominations of $500, $1,000, $5,000, and $10,000 would be discontinued immediately due to lack of use. Although they were issued until 1969, they were last printed in 1945. These notes are legal tender and may be found in circulation today; however, most notes still in circulation are probably in the hands of private numismatic dealers and collectors. "