Main city: Shelter Island
Timezone: Eastern
Phone type: Landline
Operator: Verizon New York

Shelter Island, a Town and island at the eastern end of Long Island in the U.S. state of New York. Considered part of Suffolk County, it is separated from the rest of the county by water. The population was 2,392 at the 2010 census. ^source

North American area code 631 is a telephone area code in the state of New York created on November 1, 1999, when it was split from area code 516. It is assigned solely to Suffolk County on middle and eastern Long Island. Population centers within the area code include Brookhaven, East Hampton, Huntington, Patchogue, Smithtown, Shelter Island, and Southampton Town. 631 is the first area code added to the state of New York -- other than the New York metropolitan area -- since 1954. ^source