The highest denomination of currency currently produced in the United States is the $100 bill. The $100,000 bill was the highest denomination ever made.
The United States Treasury no longer produces anything higher than $100 bills because the higher denominations do not meet the needs of the public any longer. This change was made in 1969. Denominations of $500, $1000, $5000 and $10,000 are still found in circulation today and are still considered legal tender, but the Federal Reserve Banks destroy them as they come in.
The $100,000 bill was made from December 1934 to January 1935. These were never put into circulation and were only used for transactions between Federal Reserve Banks.