Illinois comes from the word Illini, a confederation of the Cahokia, Kaskaskia, Michigamea, Moingwena, Peoria and Tamaroa Indian tribes.

Illinois's original state flag was designed in 1913 by the winner of a flag design contest (Lucy Derwent). In 1970 the Illinois state flag was redisigned by Mrs. Sanford Hutchinson. The flag's design is based upon the state's seal, which was designed by Sharon Tyndale, Illinois' secretary of state, in 1868..

The Illinois flag is all white with the Geat Seal of Illinois centered to it. A bald eagle is perched upon a rock holding a red, white, and blue shield in its talons. The shield has 13 stripes and 13 stars, representing the original 13 colonies of the United States of America. The words, "STATE," "SOVEREIGNTY," "NATIONAL," and "UNION" are written on the four folds of a banner held within the eagle's beak. The rock beneath the eagle has the dates 1818 and 1868 written on it; 1818 refers to the year Illinois became a state and 1868 refers to the date the state seal was redesigned.

The word "ILLINOIS" was added under the Great Seal in an effort to ensure that people who may not recognize the seal would still recognize which state it represented.