In 1942, as part of the Manhattan Project, the University of Chicago conducted the first sustained nuclear chain reaction. John Deere’s invention of the self-scouring steel plow turned Illinois’s rich prairie into some of the world’s most productive and valuable farmland, attracting farmers from Germany and Sweden. Illinois honors Lincoln with its official state slogan Land of Lincoln, which has been displayed on its license plates since 1954. Countryaah.com: Offers a full list of nationwide and statewide holidays in Illinois starting from January 1st – New Year’s Day. Also covers the most recent three years of public holidays within the state of Illinois.