If you went to Hawaii during World War II, you probably notice something a little funny about the money. Every greenback had a big bold "HAWAII" plastered across it. Why? In case of a Japanese invasion, of course.
Images by Atlas Obscura / Museum of American Finance
In the months after Pearl Harbour, the United States government issued a set of special Hawaii-specific banknotes. It wasn't particularly eye-catching, but the money's unique design was intended to enable the Federal Reserve to devalue the state's currency in the event of Japanese occupation, rendering it worthless. The implementation also led to a recall of all the regular banknotes in Hawaii. Each household was allowed to keep $US200, while business could keep $US500. The rest of the money was burned.
The special issue banknotes looked just like regular dollars, except "HAWAII" was emblazoned on the back in block letters. The state's name was also featured in more subtle form on the front of the bills.
Japan never occupied the state, but the "HAWAII" bills remained in circulation years after the war ended. As Atlas Obscura points out, you can now buy the bills from collectible currency vendors. Some of the bills are also on display at the Museum of American Finance. And when you marvel at Hawaii's close call with the Japanese Empire, be sure to remember that other countries didn't have such luck. Japan issued its own currency in invaded territories like Burma, Malay, and the Philippines.