Old Bethpage is a hamlet and census-designated place (CDP) located on Long Island in the Town of Oyster Bay, Nassau County, New York, USA. The population of the CDP was 5,523 at the 2010 census.
In 1695, Thomas Powell bought about 10,000 acres (40 km2) from local Indian tribes, including the Marsapeque, Matinecoc, and Sacatogue, for 140 English pounds. This land, which includes present day Bethpage, East Farmingdale, Farmingdale, Old Bethpage, Plainedge, Plainview, South Farmingdale, and part of Melville, is known as the Bethpage Purchase and is approximately 3.5 miles (5.6 km) east to west and 5 miles (8.0 km) north to south.Powell called his land Bethphage, because it was situated between two other places on Long Island, Jericho and Jerusalem, just as the biblical town of Bethphage (meaning "house of figs") was situated between Jericho and Jerusalem. Today, the Long Island place formerly called Jerusalem is known as Wantagh and Island Trees, while the placename Jericho is unaltered. Over time, Bethpage was spelled without the second "H". Powell's 14 children split up his purchase and it evolved into several farming communities, and the one in this mostly central part of the purchase retained the name "Bethpage".A railroad spur completed in 1873, known as the Bethpage Branch of the Central Railroad of Long Island, ran to a brickworks plant which had opened in Old Bethpage in the 1860s.