The smallest paper bill denomination in USD is the one dollar bill.
The one dollar bill is the smallest paper currency denomination in the United States of America. It features a portrait of George Washington, the first President of the United States, on the front, and an image of the Great Seal of the United States on the back. The one dollar bill has been in circulation since 1862, and it is commonly used for transactions such as tipping, vending machines, and small purchases. Despite being the smallest denomination of paper currency, it is still an important part of the US monetary system.