- Date of Independence: July 4, 1776 (as part of the original 13 colonies declaring independence from Britain)
- Date of Annexation to United States of America (USA): December 3, 1818 (21st state to join the Union)
- Population (2025): 12.78 million
- GDP (2025): $1.132 trillion
- Largest City: Chicago (2.61 million)
- State Capital: Springfield (117,000)
- Historical Note: Known as the “Prairie State” and “Land of Lincoln.” Home to Presidents Abraham Lincoln, Barack Obama, and Ronald Reagan (birthplace). Chicago is the third-largest U.S. city and major transportation hub. Center of Great Migration from the South. Major industrial and financial center with diverse economy including agriculture, manufacturing, and services.