The document provides information on how the United States grew and changed from the end of Reconstruction through the early 20th century. It discusses several key factors that influenced this period of growth and expansion, including territorial expansion and westward movement of settlers, new waves of immigration, rapid growth of cities and urbanization, the role of railroads, and the admission of new states. Technological advances and inventions like the railroad, mechanical reaper, and telegraph opened up new lands and markets, fueling further expansion.