Four historical events are commemorated by the four red stars on Chicago 's flag : The United States ' Fort Dearborn , established at the mouth of the Chicago River in 1803 ; the Great Chicago Fire of 1871 , which destroyed much of the city ; the World Columbian Exposition of 1893 , by which Chicago celebrated its recovery from the fire ; and the Century of Progress World 's Fair of 1933 – 1934 , which celebrated the city 's centennial . The flag 's two blue stripes symbolize the north and south branches of the Chicago River , which flows through the city 's downtown . The three white stripes represent the North , West and South sides of the city , Lake Michigan being the east side
Great Chicago Fire
Great Chicago Fire
History of Chicago