Global competition prompts the United States to expand its influence and territory, engage in conflicts around the globe, and build the Panama Canal.

Amid great political and social change, women gain a larger public role and lead the call for reform. President Theodore Roosevelt dubs his reform policies a Square Deal.

New technologies improve urban living, and a modern mass culture emerges. Reforms in public education raise literacy rates. African Americans work to end legal discrimination.

Immigration from Europe, Asia, Mexico, and the Caribbean forces cities to confront overcrowding. Local and national political corruption sparks calls for reform.

Natural resources and new ideas create a boom for industry and railroads. Government addresses corruption in business, and laborers organize for better working conditions.

The culture of the Plains Indians declines as white settlers transform the Great Plains. Meanwhile, farmers form the Populist movement to address their economic concerns.

The U.S. begins to rebuild the South, but former slaves face new challenges as support fades for the policies of Reconstruction.

In the bloody Civil War, Union forces devastate the South and defeat the Confederacy. President Lincoln narrowly wins reelection, but is assassinated as the war ends.

Slavery becomes the dominant issue in U.S. politics, leading to the birth of new political parties, the election of Abraham Lincoln, and the secession of Southern states.

New technologies create links to new markets. Economic opportunity and “manifest destiny” encourage Americans to head west. The U.S. gains territory in a war with Mexico.