13 January 1874 (United States)
The original Tompkins Square Riot. As unemployed workers demonstrated in New York City's Tompkins Square Park, a detachment of mounted police charged into the crowd, beating men, women and children indiscriminately with billy clubs and leaving hundreds of casualties in their wake.
Commented Abram Duryee, the Commissioner of Police: "It was the most glorious sight I ever saw..."
1 May 1886 (United States)
Bay View Tragedy -- About 2,000 Polish workers walked off their jobs and gathered at St. Stanislaus Church in Milwaukee, Wisconsin, angrily denouncing the ten hour workday. The protesters marched through the city, calling on other workers to join them. All but one factory was closed down as sixteen thousand protesters gathered at Rolling Mills. Wisconsin Governor Jeremiah Rusk called the state militia. The militia camped out at the mill while workers slept in nearby fields. On the morning of May 5th, as protesters chanted for the eight-hour workday, General Treaumer ordered his men to shoot into the crowd, some of whom were carrying sticks, bricks, and scythes, leaving seven dead at the scene, including a child.<2><3>
6 July 1892 (United States)
Homestead Strike -- Pinkerton Guards, trying to pave the way for the introduction of scabs, opened fire on striking Carnegie mill steel-workers in Homestead, Pennsylvania. In the ensuing battle, three Pinkertons surrendered; then, unarmed, they were set upon and beaten by a mob of townspeople, most of them women. Seven guards and eleven strikers and spectators were shot to death.<4[br />
January–March 1912 (United States)
Lawrence textile strike in Lawrence, Massachusetts, often known as the "Bread and Roses" strike. Dozens of different immigrant communities united under the leadership of the Industrial Workers of the World (IWW) in a largely successful strike led to a large extent by women. The strike is credited with inventing the moving picket line, a tactic devised to keep strikers from being arrested for loitering.
It also adopted a tactic used before in Europe, but never in the United States, of sending children to sympathizers in other cities when they could not be cared for by strike funds. On 24 February, women attempting to put their children on a train out of town were beaten by police, shocking the nation.<4><6[br />
20 April 1914 (United States)
The "Ludlow Massacre." In an attempt to persuade strikers at Colorado's Ludlow Mine Field to return to work, company "guards," engaged by John D. Rockefeller, Jr. and other mine operators and sworn into the State Militia just for the occasion, attacked a union tent camp with machine guns, then set it afire. Five men, two women and 12 children died as a result.<4><5[br />
http://en.wikipedia.org/wiki/Timeline_of_labor_issues_and_events