What are the interesting customs in America?

Every year on March 17, St Patrick's Day, the Chicago River in Chicago will be dyed green, and a parade will be held on Fifth Avenue in New York. People all over the country will wear at least one green dress, trousers, shoes, bags and even hats. St Patrick's Day is an official Christian festival to commemorate St Patrick, the patron saint of Ireland. It's also Ireland's National Day.

? Because green is the color of the Irish flag, every year on this day, Irish people and Irish descendants all over the world will wear green to celebrate this festival. St Patrick's Day is mainly popular in the northern States of the United States, because the southern States have a high proportion of African-American population and relatively few Irish descendants.