The first Monday in March is always a school holiday here in Illinois, thanks to Revolutionary War hero, Casimir Pulaski. He was a Polish cavalry officer known for his contributions in training U.S. soldiers.
Given that Chicago has the largest Polish population outside of Poland's capital city of Warsaw, we celebrate his birthday via Casimir Pulaski Day! Starting in 1977, it's been a city/county government holiday, which includes the public schools (and most private) getting the day off. I have always particularly been fond of Mr. Pulaski because his little day of honor always fell around my birthday of March 2, meaning quite often I got a "no school birthday" growing up. (Incidentally, both Indiana and Wisconsin also honor Pulaski, but not to the extent of Illinois. Though in the case of the Hoosier state, they actually designated part of I-65 from the Kankakee River to I-90 as the "Casimir Pulaski Memorial Highway").
So, hoist your bottles of Fanta Pomaranczowa and Fanta Lemonic high and drink a toast to Casimir Pulaski!