Area code 347

North American area codes 718, 347, and 929 are New York City telephone area codes in the boroughs of The Bronx, Brooklyn, Queens, and Staten Island, as well as the Marble Hill section of Manhattan. They are overlaid by area code 917, which covers the entirety of New York City.

In 1947, area code 212 was created as one of the original 86 North American area codes assigned by AT&T. It served the entire five boroughs of New York City.

On September 1, 1984, area code 718 was created as a split from 212 and was assigned to the boroughs of Brooklyn, Queens, and Staten Island.

In 1992, the borough of The Bronx and the Manhattan neighborhood of Marble Hill were moved from 212 to 718.

On October 1, 1999, area code 347 was added as an overlay to area code 718.

On December 16, 2009, the New York Public Service Commission approved an additional overlay of the 718/347 area code region. On January 22, 2010, NeuStar-NANPA issued a press release (through PR-NewsWire) that 929 is to be the new area code to further overlay the New York City 718 and 347 area codes of boroughs outside Manhattan. Area code 929 went into effect on April 16, 2011.

Area code 917 overlays area codes 718, 347, and 929, as well as area codes 212 and 646 in Manhattan.

One Manhattan neighborhood, Marble Hill, is not in the 212/646 area code but the 718/347/929 codes.

Marble Hill used to be attached to Manhattan Island. After the Harlem River Ship Canal was built in 1895, Marble Hill was physically separated from Manhattan Island. Soon after, the Spuyten Duyvil Creek was filled in with landfill, physically connecting Marble Hill to the Bronx. The Greater New York Charter of 1897 officially stated that Marble Hill is part of the borough of Manhattan.

...
Wikipedia