Another variety is the 1938-D/S, caused by dies bearing an "S" mintmark being repunched with a "D" and used to strike coins at Denver. While the actual course of events is uncertain, Bowers is convinced that the variety was created because Buffalo nickel dies intended for the San Francisco mint were repunched with the "D" and sent to Denver so they would not be wasted—no San Francisco Buffalo nickels were struck in 1938, but they were produced at Denver, and it was already known that a new design would be introduced. The 1938-D/S was the first repunched mintmark of any US coin to be discovered, causing great excitement among numismatists when the variety came to light in 1962.