The Columbine coal mine north of Denver was, by the 1920’s, the largest and most productive mine in Colorado. Next to the mine was a company town where the workers lived called Serene. Miners still worked up to 12 hours a day for six days a week under dangerous conditions. In 1927 union leaders decided to strike, demanding a pay increase from $6 to $7.50 per day and more accountability in verifying each miners’ output, which helped to figure what they were paid.
The company responded by hiring strikebreakers and surrounding Serene with fencing and barbed wire to keep out union agitators and protect the strikebreakers living there now.
On November 21, a crowd of 500 unarmed strikers marched to the gates of Serene, intending to march through the town. They were met there by armed mine guards and members of the Colorado State Police, a volunteer law enforcement group. As the crowd surged towards the gate, shots were fired overhead as warning. Soon, a machine gun fired from inside the fence, leaving 6 miners dead and 23 seriously injured.
The strike ended the following May with miners receiving a $7 per day wage.