Every year, on the same date, the Irish celebrate their patron saint, Saint Patrick. This man is the first to have introduced the concept of the Holy Trinity by symbolizing it with a clover. So every March 17, Irish people all over the world celebrate.

In the American city of Chicago, the Irish community is particularly present. Of the 2.7 million inhabitants who populate the city, approximately 200,000 are Irish, which represents approximately 7.5% of the population. They are therefore numerous to celebrate the event.

The color green, emblem of Saint Patrick's Day, therefore covers the city on this day. And since 1962, the 250 km of the Chicago River also participate in the event. Small boats dumped several kilos of fluorescein on Friday. The latter is an orange-yellow dye which becomes fluorescent green on contact with UV. This product is harmless to the river ecosystem. Indeed, it is an organic compound generally used to analyze currents, detect leaks, or infiltrations.

Once the river turns green, it's the start of seven days of festivities for the Irish in Chicago. The color change takes place early in the morning, before a big parade takes place around noon. Several activities then take place during the week of Saint-Patrick, where the beer flows freely.