Jaime Hernandez: In 2012 the U.S. Mint offered circulation strike Quarters with an "S" mint mark. The last time the U.S. Mint had offered a circulating coin with an "S" mint mark was in 1981 when it produced the 1981-S Susan B. Anthony Dollars.
The first Quarter design issued in 2012 was the El Yunque design. The 2012-S circulation strike El Yunque Quarters were only offered to collectors directly from the U.S. Mint. The coins did not go into circulation, even though they are considered circulation strikes.
The coins were only sold in 40 coin rolls and 100 coin bags. The Mint offered this new product hoping to make the coins more attractive to collectors.