Gilded Age: The Gilded Age refers to the period in U.S. history following the Civil War until around 1900 when there was rapid economic growth but also extreme wealth inequality.
Progressive Era: The Progressive Era was a period of social activism and political reform in the early 20th century (around late 1890s - early 1920s) characterized by efforts to address societal issues caused by industrialization and urbanization.
Transcontinental Railroad: The Transcontinental Railroad was a railway system built during this era that connected the eastern coast of the United States with the western coast. It played a crucial role in facilitating trade and migration across the country.