John Peter Altgeld was an American politician and the 20th Governor of Illinois, serving from 1893 until 1897. He was the first Democrat to govern that state since the 1850s. A leading figure of the Progressive movement, Altgeld signed workplace safety and child labor laws, pardoned three of the men convicted in the Haymarket Affair, and rejected calls in 1894 to break up the Pullman strike by force. In 1896 he was a leader of the progressive wing of the Democratic Party, opposing President Grover Cleveland and the conservative Bourbon Democrats. He was defeated for reelection in 1896 in an intensely fought, bitter campaign.

The Haymarket affair, also known as the Haymarket massacre, the Haymarket riot, the Haymarket Square riot, or the Haymarket Incident, was the aftermath of a bombing that took place at a labor demonstration on May 4, 1886, at Haymarket Square in Chicago, Illinois, United States. The rally began peacefully in support of workers striking for an eight-hour work day, the day after the events at the McCormick Harvesting Machine Company, during which one person was killed and many workers injured. An unknown person threw a dynamite bomb at the police as they acted to disperse the meeting, and the bomb blast and ensuing retaliatory gunfire by the police caused the deaths of seven police officers and at least four civilians; dozens of others were wounded.