Patents issued under the Patent Acts of 1790 and 1793 were not assigned numbers. Instead, they were referred to by the name of the inventor and date of issue. The Patent Office began numbering patents issued under the Patent Act of 1836; patent no. 1 was issued on July 13, 1836. Sometime in the 1950s, probably around the time the Patent Office began to experiment with computer systems, the pre-1836 patents were assigned numbers with the prefix “X”; patent no. X1 was issued on July 31, 1790.
On December 17, 1836, fire destroyed the Patent Office and most of its records, resulting in the loss of approximately 10,000 patent documents dating back to 1790. Following the disaster, Congress appropriated funds to restore the files. However, only 2,600 copies of patents have been recovered to date. Of the remaining 7,500 lost patents, only the name of the inventor, date of registration and title are known.
Table 1. U.S. Patents 1790-1836 (X Patents)