Gilded Age: A term coined by Mark Twain, referring to the late-1800s in the United States when there was significant economic growth but also social inequality.
Industrialization: The process of developing industries on a large scale, which occurred during the late-1800s and transformed societies in North America.
Transcontinental Railroad: The railway system that connected the east and west coasts of North America, facilitating transportation and trade during the late-1800s.