<p><strong>In 1914 tens of thousands of spectators flocked to the newly built Yale Bowl to cheer for the annual Yale-Harvard football game. The new stadium could seat up to 60,000 fans, far more than the roughly 2,500 who attended the first game between the college rivals, in 1875. (Related: "<a href="http://news.nationalgeographic.com/news/energy/2011/02/pictures/110204-super-bowl-green-stadiums-nfl-fifa-soccer-football-baseball-energy/">Pictures: Kickoff Time for Green Stadiums</a>")</strong></p><p dir="ltr">Football gained popularity in 19th-century America as a mixture of soccer and rugby, two sports that had long been popular in other countries. The first publicized college football game was held at least as early as 1869, just a few years before the famous Yale-Harvard games began. It was not until the 1880s, however, that this hybrid sport began to develop its own official rules, eventually becoming what we know today as American football.</p><p dir="ltr">As a new season begins, our editors searched through the archives to compile 100 years of <em>National Geographic</em> football photography.</p><p><em>—By Becky Little, photo gallery by Adrian Coakley</em></p>