The economic history of the United States can be divided into several key periods. In the 18th and early 19th centuries, the economy was primarily agrarian, relying on farming and trade. The Industrial Revolution in the late 19th century shifted the focus to manufacturing, leading to urbanization and the growth of cities. The 20th century saw significant events like the Great Depression in the 1930s, which caused widespread unemployment and economic hardship. Post-World War II, the economy experienced rapid growth, driven by technological advancements and increased consumer spending, establishing the U.S. as a global economic leader.