The Chicago race-riots of 1919 were sparked by the drowning of a black teenager named Eugene Williams on July 27 of that summer. Williams was swimming in Lake Michigan and crossed the unofficial racial barrier that separated the black and white beachgoers. In retaliation, a group of white men threw stones at Williams until he drowned. When police arrived on the scene, they refused to arrest the white men responsible, even though eyewitnesses pointed the group out. There was anger at William’s death and rising racial tensions due to the great migration of blacks to the North and their subsequent treatment by whites. Violence soon broke out between black and white Chicagoans closeby the stockyards on the South Side neighborhoods. Police were unable to end the violence, and the state militia was called in to assist. The violence ended on August 3rd. 23 blacks and 15 whites were killed, and there were over 500 people injured in the melees. Approximately 1,000 black families lost their homes to arsonists and rioters.

The season was dubbed the “Red Summer”, ripe with growing racial tension and anger. Riots broke out all over the country, in Chicago, Arkansas, Tennessee, and Washington D.C. During the wave of the great migration during World War I, many southern blacks making their homes in the North and West took open jobs in factories and warehouses. After the war ended in 1918, thousands of whites who had been fighting the war came back to see their jobs had been filled by blacks and immigrants. Furthermore, Black veterans who had fought alongside whites found themselves back in a country that denied them equality and safety, causing many to become more dissatisfied with the treatment of blacks by the hands of white Americans.

At the end of the riots, President Woodrow Wilson blamed whites for instigating the violence in Chicago and Washington D.C. He then proposed several efforts to combat the racial tensions with legislations and organizations. The Chicago Commission on Race Relations was created by city officials to help combat the causes of race riots. After the Red Summer, there were many years to come for blacks to achieve more equality under the law. The riots marked a beginning of a rise in black consciousness and refusal to remain being treated as second class citizens.
source: http://www.history.com/topics/black-history/chicago-race-riot-of-1919