On July 31, 1790 Samuel Hopkins was issued the first patent for a process of making potash, an ingredient used in fertilizer. The patent was signed by President George Washington. Hopkins was born in Vermont, but was living in Philadelphia, Pa. when the patent was granted.

The first patent, as well as the more than 6 million patents issued since then, can be seen on the Department of Commerce's United States Patent and Trademark Office website at www.uspto.gov. The original document is in the collections of the Chicago Historical Society.