William Bradley Isham, a prominent leather merchant who later worked in the banking industry, rented the land that is now Isham Park from the estate of Dr. Floyd T. Ferris in 1862 as a summer residence. Around 1864 Isham bought the property which had beautiful views of the Hudson River and the Harlem River as it was situated on a hilltop. Upon his death in 1909, parcels of the estate went to members of the Isham family. Starting in 1911 and roughly through 1922 various members gifted lots to the city to create and expand the park. The city also purchased lots throughout the area originally intended to be added to Isham park, but eventually, it was decided to add the extra lands to the newly created Inwood Hill Park and maintain the boundaries of the original Isham estates.

Current day Isham Park is a 20-acre park bordered by Seaman Avenue, Isham Street, Broadway, and 214th and 215th Street. Originally the park extended out to the Harlem River but with the creation of Inwood Hill Park in 1926, the lands were reallocated. It is said that Peter Minuit purchased the island of Manhattan from the Lenape Native Americans in Inwood Hill Park. The site is currently marked by a boulder known as Shorakkopoch Rock. The area originally intended to be added to Isham park, but eventually, it was decided to add the extra lands to the newly created Inwood Hill Park and maintain the boundaries of the original Isham estates.