This era, often called the "Age of Energy," saw the United States transition from a rural, agrarian society into a global industrial powerhouse, culminating in its emergence as a world leader after World War I. 

 

1. The Gilded Age (1877–1900)

The term "Gilded Age"—coined by Mark Twain—suggests a period of glittering prosperity covering a core of social conflict and corruption. 

• Industrial Titans: Men like Andrew Carnegie (steel), John D. Rockefeller (oil), and J.P. Morgan (finance) built massive monopolies, often called "trusts". They were simultaneously hailed as "Captains of Industry" and denounced as "Robber Barons".
• Technological Boom: Inventions like Thomas Edison’s lightbulb and Alexander Graham Bell’s telephone revolutionized daily life and industry.
• Urbanization & Immigration: Millions of "New Immigrants" from Southern and Eastern Europe arrived, fueling city growth and providing cheap labor for factories.
• Labor Unrest: Extreme wealth inequality led to violent strikes, such as the Great Railroad Strike of 1877 and the Pullman Strike. 

 

2. The Progressive Era (1890s–1920)

In response to the excesses of the Gilded Age, reformers sought to use the government to fix social and political problems. 

• Key Reforms: Trust-busting, consumer protections (e.g., the Pure Food and Drug Act), and the 19th Amendment (women's suffrage).
• Muckrakers: Investigative journalists exposed corporate greed and urban poverty, leading to increased public demand for regulation. 

 

3. World War I (1914–1918)

The U.S. initially remained neutral but entered the war in 1917. 

• Causes for Entry: Germany's unrestricted submarine warfare and the Zimmermann Telegram, which proposed an alliance between Germany and Mexico against the U.S..
• Impact: The war turned the U.S. into a global creditor and military power. Domestically, it led to the Great Migration of African Americans to Northern cities for industrial jobs. 

 

4. The Roaring Twenties (1920–1929)

The decade following the war was a time of mass consumerism and social revolution. 

• Modern Culture: The Jazz Age and Harlem Renaissance redefined American art, while "flappers" challenged traditional gender roles.
• Economic Boom: The assembly line (pioneered by Henry Ford) made cars and appliances affordable through credit.
• Conflict: This modernity clashed with traditionalism, seen in Prohibition, the revival of the KKK, and the Scopes Trial. 

The era ended abruptly with the Stock Market Crash of 1929, marking the start of the Great Depression.