This is a public domain image of $1 currency note series of 1917 of the United States. Image dimension 640 × 279 pixels, file size: 62.3 KB, MIME type: image/jpeg, a unit of currency issued by the United States of America. It is solely a work of the United States government, is ineligible for copyright, and is therefore in the public domain. Fraudulent use of this image is punishable under applicable counterfeiting laws. Both one-dollar coins and notes are issued currently. But the note form is more common. In the past, paper money was occasionally issued in denominations less than a dollar (fractional currency) and gold coins were issued for circulation up to the value of $20 (known as the "double eagle", discontinued in the 1930s).
