Richard Nixon, Lyndon Johnson

** FILE ** In this Nov. 6, 1968 file photo, Richard Nixon, left, greets the press with President Lyndon Johnson at the White House in Washington. When George Bush lifts off in his helicopter on Inauguration Day, leaving Washington to make way for Barack Obama, he may not be the only thing disappearing into the horizon. To a number of social analysts, historians, bloggers and ordinary Americans, Jan. 20 will symbolize the passing of an entire generation: the baby boomer years. (AP Photo/Charles Tasnadi, File)