The Chicago River is dyed green the Saturday before each St. Patrick's Day. The dyeing process takes place between Wabash Avenue and Columbus Drive. Hundreds of spectators watch the boats from both sides of the river between these bridges. Former Mayor Richard J. Daley is credited not only with reviving Chicago's St. Patrick's Day parade, but also proposing the idea of turning part of Lake Michigan green to celebrate the holiday. It was his boyhood friend and Chicago Plumbers Union business manager Stephen M. Bailey who suggested dyeing the Chicago River instead. The Chicago River would run green for the first time in 1962, one year after Savannah, Georgia unsuccessfully tried to dye its river green for the Irish holiday.
Early in the morning, the crew arrives at a city boat slip on the North Branch of the river. Everyone wears clothes and shoes they don't mind getting dirty and a white paper smock over their clothes. The crew hops aboard two small motorboats donated by volunteers. The larger boat, at approximately 18 feet, has a crew of four. The smaller boat, a 12-footer, has two people. The larger boat is responsible for dyeing the river, which begins when it arrives under the Michigan Avenue bridge near Wacker Drive. Three men use flour sifters to dump about 40 pounds of an environmentally friendly orange powder into the river. The fourth drives the boat. The formula for the powder, which turns the water bright green when it hits, is "top-secret". The smaller boat "chases" the larger boat and churns up the water, which helps disperse the powder across the river. Traveling the river between Wabash Avenue and Columbus Drive, the large boat snakes across the waterway dumping powder. It takes about 45 minutes for the river to turn completely green. Depending on which direction the wind is blowing, the water can stay green for up to a few days.