John Ewen was a brigadier general in New York State's National Guard during the Civil War. When the Confederate Army of Northern Virginia invaded Pennsylvania, Ewen and his three regiments were sent to reinforce the Union troops, despite a War Department policy prohibiting state militia officers above the rank of colonel from fighting in the U.S. Army. At Gettysburg, his troops operated on the flanks of the enemy, but were not directly involved in the battle. After the Union victory, Ewen and his forces returned home on July 20, 1863. He later was elected as Comptroller of the City of New York.
Eliza M. Ewen, daughter of the General, donated the land on which they lived to the City in 1916, on the condition that she be "allowed the use of the buildings and grounds for the remainder of her life undisturbed and without any changes in the grounds." The park was designed in 1935, following the death of Eliza Ewen. The steep hillside was traversed by a large stairway linking the communities of Kingsbridge and Riverdale.
The distinguished neighborhoods preserve important periods of the Bronx history and development. Kingsbridge, so named for the first bridge connecting Manhattan with the mainland in 1693, was strategically important during the Revolution in the New York Campaign and subsequently in the British defense of the city. Riverdale began as railroad station of the Hudson Division of New York Central Railroad called Riverdale-on-Hudson. In the 1860s Riverdale became a summer destination easily accessible by rail for the city's industrial and mercantile elite. The high ground overlooking the Hudson was an ideal site for the summer mansions.
The northern edge of Ewen Park was improved in 1955 when two basketball courts were installed. A rehabilitation of the walls, rails, and steps of the park was completed in 1973. The basketball courts and stairs were restored, and several new plantings were added in 1980. Council Member June M. Eisland funded the $720,000 capital reconstruction in 1999 of the large flight of stairs including new stone treads, cheek walls, handrails, and a safe durable landing pavement connecting each set of steps. New planting along the step path was also included in the reconstruction plan to help stabilize the stone. The refurbished stairway connects two diverse communities, and remains the distinguishing feature of Ewen Park.