Deer Park is a hamlet and census-designated place in the Town of Babylon, in Suffolk County, on Long Island, in New York, United States. The population was listed as 27,745 at the 2010 census. Deer Park is located in the pine barrens in the northeastern corner of the town of Babylon. It grew out of Jacob Conklin's 1610 settlement of the Half W…Deer Park is a hamlet and census-designated place in the Town of Babylon, in Suffolk County, on Long Island, in New York, United States. The population was listed as 27,745 at the 2010 census. Deer Park is located in the pine barrens in the northeastern corner of the town of Babylon. It grew out of Jacob Conklin's 1610 settlement of the Half Way Hollow Hills, later known as Wheatley Heights. Charles Wilson started what is now Deer Park in 1853 about eleven years after the Long Island Rail Road arrived in 1842-when he established a large and productive farm. A post office was opened in 1851, closed in 1872 and re-opened on July 1, 1873. Deer Park had an elementary school in 1874. Prior to 1923, the Deer Park School District took in Deer Park and Wyandanch.