516 Area Code – Nassau County, New York: Location, Time Zone & History

Area code 516 traces its origin to October 1947, when AT&T's first nationwide numbering plan grouped Nassau and Suffolk counties together with the lower Hudson Valley under area code 914. That arrangement did not last long: in 1951 Nassau and Suffolk counties were split off into their own numbering plan area and assigned this new code. The boundary shifted again on November 1, 1999, when Suffolk County was separated out and given area code 631, leaving Nassau County as the sole territory served by 516. Demand for numbers kept growing, and on January 20, 2023, area code 363 was introduced as an overlay across Nassau County, bringing mandatory ten-digit local dialing.

Beyond Hempstead, the county's largest city, the numbering plan area reaches Long Beach, Freeport, Garden City, Mineola, and Glen Cove. The local economy spans healthcare, finance and insurance, retail trade, and education, alongside a lingering aerospace and defense presence tied to the historic legacy of Grumman, once a major Long Island employer.

Nassau County also holds a notable place in American housing history as home to Levittown, one of the first mass-produced suburban developments built in the United States after World War II, a model that shaped suburban growth well beyond the region.