Third Bureau Number Series (1940-present)
In 1940, so many aircraft were being ordered as a result of President Franklin Roosevelt's rearmament program that it was found necessary to terminate the second series at 7303 in order to avoid confusion with aircraft having late numbers in the original series that were still in service. A third (and final) series of Bureau Numbers was started with 00001 (using 5 digits from the beginning. When the third series reached 99999 in 1945, it was allowed to continue into six digits. This series of numbers continues in the present day. It has now reached over 165000.