What is crane paper made from?

Crane Paper is the name of the company that makes the paper for U.S. banknotes, along with writing papers, envelopes, etc. for retail sale.

The paper used in banknotes is a special formulation with a high cotton content so that it will put up with repeated foldings, accidents such as going through a washing machine, etc. In addition it has tiny blue and red fibers, a watermark, and a special UV-sensitive security strip embedded in it to defeat photocopiers.

However, Crane Paper also has very powerful lobbyists that have prevented a number of major changes to U.S. currency, in particular ending production of the $1 bill in favor of dollar coins.