Statistics for occurrence #1 of “Illinois” in chapter 6 of The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 10: The Armies and the Leaders.:

...s, Twenty-eighth Pennsylvania, Ninth New York. Twelfth Massachusetts, First Delaware, and other regiments; at Stone's River, December 31, 1862, by the Eighteenth United States Infantry, Twenty-Second Illinois , and other regiments; at Gettysburg, by the Twenty-Fourth Michigan, one hundred and eleventh New York, First Minnesota, one hundred and Twenty-sixth New York, and one hundred and fifty-first Pennsylv...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Illinois (Illinois, United States) 6,200 40 0 0 0 user votes
Illinois (New Mexico, United States) 4 0 0 0 0 user votes
Illinois (Oregon, United States) 2 0 0 0 0 user votes
Illinois (Colorado, United States) 0 0 0 0 0 user votes
Illinois (Illinois, United States) 0 0 0 0 0 user votes
Illinois (New Mexico, United States) 0 0 0 0 0 user votes

† This entity has been selected by the automated classifier as the most likely match in this context. It may or may not be the correct match.