1) The period after the Civil War known as Reconstruction saw African Americans gain rights but the South enact Jim Crow laws to oppress them and disagree over how to rebuild.
2) During the Gilded Age, a small group of wealthy industrialists controlled much of the nation's wealth while many Americans faced poverty, including African Americans under Jim Crow, Native Americans on reservations, and low-paid immigrant workers.
3) In response to the inequality between the wealthy and poor, labor unions formed and the Progressive movement aimed to address social injustices, while the philosophy of laissez-faire argued for limited government regulation of business.