For more than four hundred years, the frontier regions of America were an ever-shifting area that spanned an entire continent. From the tidewater regions of New England to the California coast, the American frontier moved steadily west for more than a dozen generations.

Because the regions kept changing, the American frontier is defined more by its people than its actual geographic boundaries. The story of the American frontier may best be seen through the eyes of European American and African American people who settled the land—and the Native Americans who lost their land in the process. Pioneers were all sorts of people—rich, poor, ex-slaves, saints, and sinners. But they seemed to have one idea in common: that a better world lay over the next horizon. So they pushed and pushed westward until the frontier was conquered and a modern nation...