Periods prior to period-7 refer to the historical eras and events that occurred in the United States from its founding until the onset of World War II. These periods include significant developments such as colonialism, the American Revolution, the formation of a new nation, the Civil War, and the Reconstruction era, all of which laid the foundation for modern America. Understanding these earlier periods helps to contextualize the changes and continuities that shaped the nation leading up to the 20th century.