Formed by megaton volcanic blasts, sculpted by glaciers and boiling water, Yellowstone's singular landscape became the world's first national park in 1872. Its more than 2.2 million acres straddling three Western states first attracted adventurers on horseback and later the adventurous elite by railroad.
In 1903, during a dedication at Yellowstone's northern entrance in Gardiner, Mont., President Theodore Roosevelt expressed his hope "to see a steadily increasing number of our people take advantage of its attractions." He needn't have worried. During its 127th summer as an official American playground, more than 2.9 million visitors toured this terrain of rugged mountains, spectacular deep valleys and the world's greatest concentration of steam-spewing geysers.
The crown jewel among the park's nearly 300 geysers remains Old Faithful, which takes its name from a reliable pattern of eruption that has changed little over the last century. On average, it bursts forth every 77 minutes and can hurl 8,400 gallons of scalding water into the air during a five-minute display.
Like the other destinations featured in this edition of the Travel section, Yellowstone is a force that has shaped the way Americans explore the world around them.