The Norman Rockwell Museum

The Norman Rockwell Museum is an art museum in Stockbridge, Massachusetts, dedicated to the art of Norman Rockwell. It is home to the world's largest collection of original Rockwell art. In addition to 574 original works of art by Rockwell, the museum also houses the Norman Rockwell Archives, a collection of over 100,000 various items, which include photographs, fan mail, and various business documents. In 2014, the Famous Artists School donated its archives, including process drawings by Rockwell, one of its founding faculty members in 1948, to the museum. 

Source: nrm.org