| Bessemer process | A method for mass-producing steel cheaply by blowing air through molten iron, enabling the construction of railroads, bridges, and skyscrapers that defined Gilded Age industrial growth. |
| Horizontal Integration | A business strategy of buying out competitors at the same production level, used by Rockefeller to build Standard Oil into a near-monopoly controlling roughly 90 percent of U.S. oil refining. |
| Gospel of Wealth | Andrew Carnegie's argument that wealthy industrialists had a moral obligation to use their fortunes philanthropically, funding libraries, universities, and civic institutions. |
| Dawes Act | An 1887 law that broke up communal tribal lands into individual allotments, undermining Native sovereignty and transferring millions of acres to white settlers under the guise of assimilation. |
| American Federation of Labor (AFL) | A federation of skilled craft unions led by Samuel Gompers that focused on collective bargaining for higher wages, shorter hours, and safer conditions rather than broad social reform. |
| Haymarket Affair | A 1886 Chicago labor rally that turned violent when a bomb was thrown at police; the backlash severely damaged the Knights of Labor and set back the broader labor movement. |
| Chinese Exclusion Act | An 1882 federal law barring Chinese laborers from entering the United States, the first immigration restriction based on nationality, reflecting nativist and racial anxieties in the Gilded Age. |
| Hull House | A settlement house founded by Jane Addams in Chicago in 1889 that provided education, childcare, and social services to immigrants and the urban poor, becoming a center of Progressive reform. |
| Plessy v. Ferguson | An 1896 Supreme Court ruling that upheld racial segregation under the 'separate but equal' doctrine, entrenching Jim Crow laws and effectively ending most Reconstruction-era political gains for African Americans. |
| Populist Party | The People's Party, formed in 1892 by agrarian activists, called for government ownership of railroads, a graduated income tax, direct election of senators, and free coinage of silver to relieve farm debt. |
| Interstate Commerce Act of 1887 | The first federal law to regulate railroads, establishing the Interstate Commerce Commission to oversee rates; weakly enforced in the Gilded Age but a precedent for Progressive Era regulation. |
| Cross of Gold Speech | William Jennings Bryan's 1896 address at the Democratic National Convention arguing for silver coinage to help debtors and farmers, which fused Populist and Democratic agendas but failed to win the presidency. |
| How the Other Half Lives | Jacob Riis's 1890 photojournalistic expose of tenement conditions in New York City that sparked public awareness of urban poverty and calls for housing and labor reform. |
| Social Darwinism | The application of evolutionary competition to human society, used in the Gilded Age to justify economic inequality and racial hierarchies as natural outcomes of competition rather than products of policy. |