The document summarizes key events and developments in the United States between 1800-1850, a period of growth for a young nation. Some of the major events included the Louisiana Purchase which doubled the country's size, the War of 1812 which helped establish the US as an independent nation, westward expansion and the Mexican-American War which added territory from Texas to California, and the California Gold Rush which spurred rapid population growth. The period also saw the beginnings of industrialization, new transportation technologies, and social reforms.