If you aren't from Illinois, you might not know what Casimir Pulaski Day is. But if you grew up in Illinois and don't live there anymore, you may be wondering why you don't have this holiday—which is celebrated the first Monday each March—off from work or school.

WBEZ Chicago has a great guide to the holiday, which commemorates Casimir Pulaski, one of Illinois' favorite sons (who died decades before Illinois even became a state).

Casimir Pulaski was a talented military leader and brilliant battlefield tactician who, in the 1770s, had to leave his native Poland after participating in the unsuccessful wars to oust Stanisław II, a king put in place to rule at the behest of the Russians. While in exile in Paris, Pulaski met and befriended Ben Franklin, who recruited him for the American Revolution's cause.

After initial resistance from Colonists reluctant to place a foreigner in an important military post, Pulaski, serving informally, proved his mettle at Brandywine and Germantown. George Washington was so impressed that he made Pulaski a Brigadier General and the first Commander of the American Cavalry. Soon after this recognition, in 1779, Pulaski died from wounds sustained at the Siege of Savannah.

Flash-forward a century or so to Chicago, which, by the late 1800s, had become a worldwide capital for Polish emigration. In the 1930s, Polish citizens in the city, who had faced discrimination, had taken to championing Casimir Pulaski as an example of a great Polish-American hero in the name of cultural integration and understanding. Tributes to the general sprouted up around town—most notably the renaming of a major thoroughfare "Pulaski Road."

Pulaski's profile in Chicago grew, and in 1977, the Polish American Congress successfully lobbied for a law in Illinois designating the first Monday of March as “Casimir Pulaski Day.” At first, it was merely a commemorative holiday, meaning schools and other institutions stayed open, but in 1985, Pulaski Day became a full public holiday for schools. Depending on where you were in the state, other government offices and some banks would also choose to close on that Monday.

Currently, Casimir Pulaski Day is less prevalent than it was in the '80s and '90s. It became an optional holiday for schools in 2009, and, according to WBEZ, "74 percent of the districts chose to keep school open on Pulaski Day." In 2012, Chicago Public Schools tossed the holiday altogether during negotiations between Mayor Rahm Emanuel and the teachers union.

While Pulaski the day may be waning, the man won't be forgotten in Chicago any time soon, as his name and image appear all over town (check out the Polish Museum of America for more). And, in 2009, former Chicago resident Barack Obama signed a joint resolution of the House and the Senate to make Casimir Pulaski an honorary United States citizen.