Acknowledging the country's turbulent history, Clinton quoted former President Abraham Lincoln, saying America's journey had been, in Lincoln's words, "piled high with difficulty."

Acknowledging the country's turbulent history, Clinton quoted former President Abraham Lincoln, saying America's journey had been, in Lincoln's words, "piled high with difficulty."

As America marks its 250th year this July Fourth, former Presidents Clinton, Bush and Obama shared their messages to the country on its milestone birthday.