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Visitors to CarolinaFest, Charlotte's Labor Day street festival, get caught in a downpour September 3, 2012 in Charlotte, North Carolina. The Democratic National Convention begins tomorrow in Charlotte and runs through Thursday. (Photo by Scott Olson/Getty Images)

U.S. celebrates Labor Day

Parades, picnics and politicians celebrated the American worker on Labor Day, with President Barack Obama seeking votes from Ohio union members and rivals for Senate seats marching in Massachusetts and Virginia.