US celebrates its 237th Independence Day

Fireworks explode over Lake Union during the Seafair Summer Fourth event Thursday, July 4, 2013, as seen from Gas Works Park in Seattle, Wash. AP Photo

Fireworks explode over Lake Union during the Seafair Summer Fourth event Thursday, July 4, 2013, as seen from Gas Works Park in Seattle, Wash. AP Photo

Fireworks explode over the Philadelphia Museum of Art during an Independence Day celebration, Thursday, July 4, 2013, in Philadelphia. AP Photo

Lightning flashes during Independence Day fireworks as viewed atop Mt. Washington on Grandview Ave. in Pittsburgh, Thursday, July 4, 2013. AP Photo

Fireworks explode over the Philadelphia Museum of Art during an Independence Day celebration, Thursday, July 4, 2013, in Philadelphia. AP Photo

Fireworks explode over the Philadelphia Museum of Art during an Independence Day celebration, Thursday, July 4, 2013, in Philadelphia. AP Photo

Residents and visitors of Alexander's Lake sit out on their docks and in small boats as they watch neighborhood fireworks as they celebrate Independence Day, Thursday, July 4, 2013, in Dayville, Conn. AP Photo

Fireworks light up the Empire State Building along the Manhattan skyline during Macy's 37th Annual Fourth of July fireworks show, Thursday, July 4, 2013, in New York. AP Photo

Al Mitchell, of Barnstead, N.H., salutes during the national anthem before the Boston Pops Fourth of July Concert at the Hatch Shell in Boston, Thursday, July 4, 2013. AP Photo

Fireworks burst over the Hatch Shell during the finale of the Boston Pops Fourth of July Concert in Boston, Thursday, July 4, 2013. AP Photo

Audience members join arms as the Boston Pops play God Bless America during their Fourth of July Concert at the Hatch Shell in Boston, Thursday, July 4, 2013. AP Photo

First lady Michelle Obama, left, with members of the military wave during a Fourth of July celebration with military members and their families, on the South Lawn of the White House in Washington, Thursday, July 4, 2013. AP Photo

President Barack Obama, holds a baby as he and first lady Michelle Obama, not in picture, greets members of the military and their families during a Fourth of July celebration on the South Lawn of the White House in Washington, Thursday, July 4, 2013. AP Photo

New York City Mayor Michael Bloomberg, left, Secretary of the Interior Sally Jewell, second from left, New Jersey Sen. Robert Menendez, second from right and superintendent of the Statue of Liberty National Monument David Luchsinger cut a ceremonial ribbon during the reopening ceremony of the Statue of Liberty, Thursday, July 4, 2013 at in New York. The Statue of Liberty reopened on the Fourth of July, months after Superstorm Sandy swamped its little island in New York Harbor as Americans across the country marked the holiday with fireworks and barbecues. AP Photo

The White House is adorned in preparation for the a Fourth of July celebration on the South Lawn of the White House in Washington, Thursday, July 4, 2013, hosted by President Barack Obama and first lady Michelle Obama. AP Photo