Suffolk County, New York

Suffolk County (/ˈsʌfək/) is the easternmost county in the U.S. state of New York. It comprises the eastern two-thirds of Long Island, bordered to its west by Nassau County, to its east by Gardiners Bay and the Atlantic Ocean, to its north by Long Island Sound, and to its south by Great South Bay.

As of the 2020 United States census, the county's population was 1,525,920, its highest decennial count ever, making Suffolk the fourth-most populous county in the State of New York, or the most populous if the New York City boroughs are not considered counties. Its county seat is Riverhead, though most county offices are in Hauppauge. The county was named after the county of Suffolk in England, the origin of its earliest European settlers.

Suffolk County incorporates the easternmost extreme of the New York City metropolitan area. The geographically largest of Long Island's four counties and the second-largest of New York state's 62 counties, Suffolk County is 86 miles (138 km) in length and 26 miles (42 km) in width at its widest (including water). Most of the island is near sea level, with over 1,000 miles of coastline.

Like other parts of Long Island, the county's high population density and proximity to New York City has resulted in a diverse economy, including industry, science, agriculture, fishery, and tourism. Major scientific research facilities in Suffolk County include Brookhaven National Laboratory in Upton, Cold Spring Harbor Laboratory in Huntington, and Plum Island Animal Disease Center on Plum Island. The county is home to Stony Brook University in Stony Brook and Farmingdale State College in Farmingdale.