Humans have been exploring boulders in America for hundreds of years, going back to the Native Americans who lived in and around many of today’s bouldering areas. In the 1950s and ‘60s, John Gill began taking gymnastics to the rocks, seeking challenges on small cliffs and boulders from Illinois to the Tetons to the Black Hills to Colorado. But he was largely alone until well into the 1970s and ‘80s, when bouldering started to become seen as a pursuit in its own right. Given the size and geological diversity of the US, we may very well have the most—and most varied—bouldering in the world. We also have an extraordinary legacy of classic problems from V0 to V16, with seemingly endless potential left. To list the 25 best problems in America is a challenge.