Casimir Pulaski Day is a local holiday officially observed in Illinois, on the first Monday of March in memory of Casimir Pulaski, a Revolutionary War cavalry officer born in Poland as Kazimierz Pułaski.
Casimir Pulaski Day is a legal holiday in Illinois. It celebrates the birthday of Pulaski, a Polish-born soldier who made a significant contribution to American independence. … Chicago is known for its large population of Polish immigrants who came to the United States during the 19th century.