U.S. population distribution by age, 1900 through 2060 Posted on Tuesday, August 13th, 2013 at 7:15 am. PTWritten by Jim Dalrymple This is cool. Be sure to watch the graph changes at the bottom. tag A couple of things that get hidden by the way the graph is presented: 1) an increasing number of categories means that although percentage distributions appear to go down, there is no indication the real values of those categories are decreasing (the “bigger pie” problem), 2) because of the increasing number of categories combined with representation as percentages, variance between the categories goes down, so differences, while they may be real in magnitude, appear smaller in later years, and 3) as a consequence, the “echo boom” (kids of baby boomers) and the “echo-echo boom” (grandkids) are not as noticeable. Present, but less visible.Of course, these echo booms are further masked, as a sizable chunk of the U.S. population growth is due to immigration rather than birth rate, but are visible in states with lower immigration.