Following the Japanese attack on Pearl Harbor on December 7, 1941, the U.S. government worried that Hawaii might be overrun by the Japanese. As a result, it issued emergency $1 Silver Certificates for use only in Hawaii during World War II. They have a brown seal instead of the usual blue seal, plus the word “HAWAII” on both sides to make them easy to identify… and easy to declare worthless if they had fallen into enemy hands. Fortunately, that never happened, but just a few remain for today’s collectors.