Old Westbury is an extremely affluent village in Nassau County, in the U.S. state of New York, on the North Shore of Long Island. As of the 2010 United States Census, the village population was 4,671. The Incorporated Village of Old Westbury is located in both the Town of Oyster Bay and the Town of North Hempstead.
Old Westbury is one of the richest villages in the country as well as the second-richest zip code in the New York State, topped only by Harrison in Westchester County. In 2007, Business Week dubbed Old Westbury as New York's most expensive suburb. Old Westbury Gardens has been recognized as one of the three best public gardens in the world by Four Seasons Hotels magazine. The Long Island campus of the New York Institute of Technology is a life sciences and cybersecurity research institution located in Old Westbury.
Old Westbury is located at 40°46′55″N 73°35′50″W (40.782038, −73.597236).
According to the United States Census Bureau, the village has a total area of 8.6 square miles (22 km2), all of it land.
As of the census of 2000, there were 4,228 people, 1,063 households, and 967 families residing in the village. The population density was 493.9 people per square mile (190.7/km2).