The 150-year-long conquest of the American West was one of the most colorful eras of American history. From the moment that small bands of settlers set out across the Appalachian Mountains in the 1750s to the closing of the frontier around 1890, Americans sprawled and fought their way across thick forests, vast prairies, and soaring mountains, claiming as their own lands once inhabited by Native American tribes, or by Spanish or Mexican settlers, if they were inhabited at all. Fierce battles with Native Americans, protracted wars with the British and the Mexicans, and the sheer difficulty of taming the wilderness shaped the expanding American nation. But when people today think of the "Wild West," they do not think of land claims, wars, or early conflicts with Native Americans in the forested East. Instead they think of gunfights in dusty western towns, masked outlaws holding up...