[3][4] In the summer of 1781, George Washington summoned from Rhode Island General Rochambeau's 5,000 French troops to join him in a campaign against the British.

In the early 20th century, a committee composed of William Sloane, Moses Taylor, Joseph C. Baldwin, Jr., Edwin G. Merrill, John Henry Towne, Winthrop Cowdin, Cornelius R. Agnew and Hiram E. Manville was set up to organize the creation of a new hospital to serve northern Westchester County.

[7] In response, the hospital expanded to 50-rooms in April 1925, and, demonstrating its continual evolution to meet the needs of an ever more sophisticated healthcare system, added a state-of-the-art radiology facility.

[8] Two decades later the hospital opened the DeWitt Wallace Pavilion, bringing it to a total of 259 beds in 1973 and allowing NWH to enter a new age of patient-centered care.

NWH modernized its surgical services facility in April 2016 to include six new operating rooms and 13 private pre- and post-anesthesia care beds.

On September 2, 2020, Northern Westchester Hospital opened its cardiac catheterization lab, part of the Seema Boesky Heart Center.