This addition houses the largest collection of local history and genealogy in northeastern Pennsylvania with roughly 15,000 historical texts and materials about the Easton area and Northampton County.

[3][12] The company was founded in order to provide books to the citizens of Easton, however only patrons who supported the library with a yearly subscription fee were allowed access to the collection.

During the Civil War, the subscription service suffered due to a high number of Easton citizens enlisting in the Union Army.

In 1901, the Carnegie Corporation received plans from the Easton Library Association asking for a donation for a new building to be constructed on Church Street.

The committee sent plans for a two-story Modern Renaissance building, measuring 90 by 70 feet (27 by 21 m), on the best available piece of property in town, an old graveyard no longer in use.

[12] Included in the plans were a fireproof vault for the protection of books of rare and historic value, and an auditorium with a seating capacity of 400 to 500 people.

To pay for the new room the Friends of the Library contacted the National Endowment for the Humanities and secured a $100,000 (equivalent to $553,000 in 2023 dollars),[18] grant to assist in fundraising.

[12][16] The Marx Room holds many of Easton's most historic relics, including the oldest known map of the area dating back to the late 18th century, which was hand drawn by Charles de Krafft who surveyed the area for Thomas Penn, son of William Penn, founder of the colonial-era Province of Pennsylvania.

The map outlines the original 1,000 acres (400 ha) of Easton which Thomas Penn received in 1736 in order to keep track of who was living on each plot of land, and as a resource for town lots to be rented out to farmers and other settlers moving to the region.

[10][11] The flag was also later given to Captain Abraham Horn's Company as they left to march tos Camp DuPont in Marcus Hook during the War of 1812.

The plans for the new $400,000 (equivalent to $943,000 in 2023 dollars),[18] library had been initiated in 1983, and money was raised by the township Business, Industrial and Professional Association Incorporated.