FLASHBACK: As America turns 250, here's how the nation celebrated its biggest birthdays

America's milestone anniversaries have given generations of Americans an opportunity to reflect on the nation's history, values and progress. From the Centennial in 1876 to the Bicentennial in 1976, celebrations have had parades, fireworks, historical reenactments, speeches and other patriotic traditions honoring the Declaration of Independence and the nation's founding in 1776. As Americans celebrated the country's 250th anniversary on July 4, those traditions carried into the semiquincentennia