National Park Quarter Error Coins

America's quarters are "workhorses" of commerce, used in vast quantities each day in coin-operated devices. Billions of National Park quarters have been issued since the start of the series in 2010, requiring high-speed production at the Philadelphia and Denver Mints (where regular-issue National Park quarters are made). The possibility of mistakes from mechanical malfunction or human error is great. Yet, while doubling has been seen on some issues of the series, to date there haven't been any major errors like those found in the 1999-2008 Statehood quarter series. However, there's no telling what may be awaiting discovery by keen-eyed individuals.