Labor unions flourished for a number of reasons: abysmal working conditions; a lack of concern for workers’ safety; low pay and nonexistent benefits; and a 10-12 hour workday. The Knights of Labor, one of the strongest unions, focused on achieving an eight-hour day. After a worker was killed at a labor rally, the crowd broke out in violence. Firing into the crowd, the police killed four workers. The long-term effect of this riot was widespread fear of unionism, and a delay in the acceptance of the eight-hour day.