** ADVANCE FOR MONDAY, JAN. 12 AND THEREAFTER -- FILE ** In this Dec. 2, 1984 black-and-white file photo, President Reagan and first lady Nancy Reagan return to 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, File)