June 30 (UPI) -- This year's July 4 fireworks display in Washington, D.C.,will be the largest ever held there, organizers said Tuesday. The pyrotechnics on the National Mall will also start later as the capital marks the nation's 250th anniversary. Jeff Carroll, interim chief of the D.C. Metropolitan Police Department, said the holiday will have "the largest display of fireworks our city has ever seen," CBS News reported . A representative for Freedom 250, the public-private partnership