In the late 1800's and early 1900's
America was being rapidly industrialized. The
economic and
industrial development of the
nation was "led" by the "Captains of Industry". Fed by large amounts of
cheap labor and cheap resources, these people built themselves huge
industrial empires and massed fortunes for themselves. Prime examples include
John D. Rockefeller,
Andrew Carnegie, and the financier
J.P. Morgan.
Unfortunately, their empires were built on the blood of the common workers, whom they shamelessly exploited to gain as much profit was possible.
A combination of horrid working conditions, measly pay, and suppression of the workers' voices was their method to keep costs low ("Cut cost" was apparently Carnegie's motto). Strikes were viciously broken with either violence or scabs (immigrant workers that work even cheaper than the regular workers, unfortunately, they were untrained and died by the dozen in steel mills and other dangerous environments). For an example of the violence used, see the Homestead Strike.
Working conditions were disgusting in all industries, be it steel, meat packing, or mining. It was only until Upton Sinclair wrote his book "The Jungle" did the people of America learn what they were really eating. There is no injury compensation or sick leave.
The exploitation of the common worker was one of the most blatant atrocities in modern history that went unpunished because it was hidden behind the veneer of wealth brought by industrialization. I'm not suprised Karl Marx argued that capitalism was doomed under those conditions.