What is 631 area code?

The 631 area code serves Suffolk County on Long Island, New York. It was created in 1999 as a split from the 516 area code, which became solely associated with Nassau County. This split was necessary due to the increasing population and telecommunication demands in the region. The 631 area code is geographically large, covering the eastern two-thirds of Long Island. It includes major towns and cities such as Smithtown, Brookhaven, and Riverhead.