Because the United Mine Workers had essentially left Colorado in defeat a decade earlier , the IWW began organizing Colorado coal miners in 1925 .
The United Mine Workers responded by banning IWW card holders from membership in the UMW .
Because the UMW     had essentially left Colorado in defeat a decade earlier , the IWW began organizing Colorado coal miners in 1925 .
The United Mine Workers responded by banning IWW card holders from membership in the UMW .