The 1901-S Barber Quarter had a total mintage of 72,664 pieces struck for circulation at the San Francisco Mint. This represented the lowest mintage for the series at the time, however it would later be undercut by the 1913-S which had a mintage of 40,000 pieces. Nonetheless, the extensive circulation took a heavier toll on the 1901-S, making it the rarer of the two issues with perhaps 1,500 to 2,000 examples surviving in all grades. The majority of these are well-circulated, often barely recognizable, while only a distinct minority have managed to survive in uncirculated condition.
Compared to other quarters of the early 20th century, the mintage of the 1901-S quarter was extremely low. Virtually all other issues of this period had a mintage at least ten times greater, with the Philadelphia issues usually having the highest mintages. While the San Francisco Mint typically produced a smaller output, the numbers were still sizable with more than 1.5 million quarters struck in both 1900 and 1902, the years immediately before and after the key date rarity. Unlike 1906, there was no natural disaster in San Francisco (the earthquake of that year did have some influence on the mintages of the circulating coins struck at the San Francisco Mint) so there must have been some other reason for the unusual drop in production.
Many have speculated that the San Francisco Mint may have had an adequate supply of freshly minted quarters from other years still in storage, thus they planned to pay these out prior to striking large quantities of additional quarters.This scenario seems to be a likely possibility which would account for the limited production for the denomination during the year.
The small number of newly minted quarters would soon end up in circulation and it would not be for another few decades until the issue attracted some attention above other higher mintage issues. By this time, much of the original mintage had been lost or survived in well worn or damaged condition. Accordingly, the supply of uncirculated examples of this issue is extremely limited.