The Washington Post recently published this very interesting, animated chart that shows the distribution of the U.S. population by age over time, starting at 1900 and ending with the Census Bureau’s forecasts between now and 1960.
Check it out here:

http://www.washingtonpost.com/blogs/wonkblog/wp/2013/08/13/this-amazing-animated-chart-shows-the-aging-of-america/