The United Mine Workers of America begin a strike against the Rockefeller-owned Colorado Fuel & Iron Company, sparking the Colorado Coalfield War.

The United Mine Workers of America is a North American labor union best known for representing coal miners. Today, the Union also represents health care workers, truck drivers, manufacturing workers and public employees in the United States and Canada. Although its main focus has always been on workers and their rights, the UMW of today also advocates for better roads, schools, and universal health care. By 2014, coal mining had largely shifted to open pit mines in Wyoming, and there were only 60,000 active coal miners. The UMW was left with 35,000 members, of whom 20,000 were coal miners, chiefly in underground mines in Kentucky and West Virginia. However it was responsible for pensions and medical benefits for 40,000 retired miners, and for 50,000 spouses and dependents.

John Davison Rockefeller Jr. was an American financier and philanthropist. Rockefeller was the fifth child and only son of Standard Oil co-founder John D. Rockefeller. He was involved in the development of the vast office complex in Midtown Manhattan known as Rockefeller Center, making him one of the largest real estate holders in the city at that time. Towards the end of his life, he was famous for his philanthropy, donating over $500 million to a wide variety of different causes, including educational establishments. Among his projects was the reconstruction of Colonial Williamsburg in Virginia. He was widely blamed for having orchestrated the Ludlow Massacre and other offenses during the Colorado Coalfield War. Rockefeller was the father of six children: Abby, John III, Nelson, Laurance, Winthrop, and David.

The Colorado Fuel and Iron Company (CF&I) was a large steel conglomerate founded by the merger of previous business interests in 1892. By 1903 it was mainly owned and controlled by John D. Rockefeller and Jay Gould's financial heirs. While it came to control many plants throughout the country, its main plant was a steel mill on the south side of Pueblo, Colorado, and was the city's main industry for most of its history. From 1901 to 1912, Colorado Fuel and Iron was one of the Dow Jones Industrials. The steel-market crash of 1982 led to the decline of the company. After going through several bankruptcies, the company was acquired by Oregon Steel Mills in 1993, and changed its name to Rocky Mountain Steel Mills. In January 2007, Rocky Mountain Steel Mills, along with the rest of Oregon Steel's holdings, were acquired by EVRAZ Group, a Russian steel corporation, for $2.3 billion.