The Pacific Railroad Society is one of the oldest railroad enthusiast organizations in the country. It was formed in 1936, when six railfans in the Los Angeles area banded together as the "Railroad Boosters." In 1949, a new name was adopted: Pacific Railroad Society. It became a non-profit in 1957, and changed to a charitable public-benefit organization in 1980 to facilitate raising funds and soliciting tax-deductible donations to establish a library and museum.
In the 1990’s, the City of San Dimas was using the Depot as a senior center. The City then built a new senior center closer to City Hall. Because the Depot was an excellent example of the Art Deco style that influenced the Santa Fe railroad stations of the time, PRS decided to seek a lease in order to preserve the building and its history.
Excursions were also an important part of the group from its beginning, and included visits to such now-legendary places as Pacific Electric's Torrance Shops, the Mount Lowe Railway, and San Luis Obispo's narrow-gauge Pacific Coast Railway.
All PRS activities are carried out on a volunteer basis. There are no paid staff and no director salaries or stipends. Operating funds are raised through membership dues, donations, rail excursions, and gift shop sales.