Photo, Ludlow Tent Colony, prior to the Ludlow Massacre. Caption reads: "THE COLORADO TENT COLONY SHOT UP BY THE MILITIA, Ludlow, a canvas community of 900 souls, was riddled with machine guns shooting 400 bullets a minute. Then the tents were burned. The site is private property leased by the miners' union, which has supported the colony seven months."
Areas of the
Rocky Mountains have veins of coal close to the surface of the land, providing significant and relatively accessible reserves. In 1867, these coal deposits caught the attention of
William Jackson Palmer, then leading a survey team planning the route of the
Kansas Pacific Railway. The rapid expansion of
rail transport in the United States made coal a highly valued commodity, and it was rapidly commercialized.
At its peak in 1910, the coal mining industry of Colorado employed 15,864 people, accounting for 10 percent of those employed in the state.
 Colorado's coal industry was dominated by a handful of operators. The largest,
Colorado Fuel and Iron, was the largest coal operator in the west, as well as one of the nation's most powerful corporations, at one point employing 7,050 individuals and controlling 71,837 acres (290.71 km2) of coal land.
 The Colorado Fuel & Iron Company was purchased by
John D. Rockefeller in 1902, and nine years later he turned his controlling interest in the company to his son,
John D. Rockefeller, Jr., who managed the company from his offices at
26 Broadway in
Mining was dangerous and difficult work.
Colliers in Colorado were at constant risk for explosion, suffocation, and collapsing mine walls. In 1912, the death rate in Colorado's mines was 7.055 per 1,000 employees, compared to a national rate of 3.15.
 In 1914, the
United States House Committee on Mines and Mining reported that "Colorado has good mining laws and such that ought to afford protection to the miners as to safety in the mine if they were enforced, yet in this State the percentage of fatalities is larger than any other, showing there is undoubtedly something wrong in reference to the management of its coal mines."
 Miners were generally paid according to tonnage of coal produced, while so-called "dead work", such as shoring up unstable roofs, was often unpaid.
 According to historian Thomas G. Andrews, the tonnage system drove many poor and ambitious colliers to gamble with their lives by neglecting precautions and taking on risk, with consequences that were often fatal.
 Between 1884 and 1912, mining accidents claimed the lives of more than 1,700 Coloradans.
 In 1913 alone, "104 men would die in Colorado’s mines, and 6 in the mine workings on the surface, in accidents that widowed 51 and left 108 children fatherless."
Colliers had little opportunity to air their grievances. Many colliers resided in
company towns, in which all land, real estate, and amenities were owned by the mine operator, and which were expressly designed to inculcate loyalty and squelch dissent.
Welfare capitalists believed that anger and unrest among the workers could be placated by raising colliers' standard of living, while subsuming it under company management. Company towns indeed brought tangible improvements to the lives of many colliers and their families, including larger houses, better medical care, and broader access to education.
 However, ownership of the towns provided companies considerable control over all aspects of workers' lives, and this power was not always used to augment public welfare. Historian
Philip S. Foner has described company towns as "
feudal domain[s], with the company acting as lord and master. ... The 'law' consisted of the company rules. Curfews were imposed. Company guards - brutal thugs armed with machine guns and rifles loaded with
soft-point bullets - would not admit any 'suspicious' stranger into the camp and would not permit any miner to leave." Furthermore, miners who raised the ire of the company were liable to find themselves and their families summarily evicted from their homes.
Frustrated by working conditions which they felt were unsafe and unjust, colliers increasingly turned to
unionism. Nationwide, organized mines boasted 40 percent fewer fatalities than nonunion mines.
 Colorado miners had repeatedly attempted to unionize since the state's first strike in 1883. The
Western Federation of Miners organized primarily hard rock miners in the
silver camps during the 1890s. Beginning in 1900, the United Mine Workers of America began organizing coal miners in the
western states, including southern Colorado. The union decided to focus on the Colorado Fuel & Iron Company because of its harsh management tactics under the conservative and distant Rockefellers and other investors. To break or prevent strikes, the coal companies hired
strike breakers, mainly from Mexico and southern and eastern Europe. The Colorado Fuel & Iron Company's management mixed immigrants of different nationalities in the mines, a practice which discouraged communication that might lead to organization.