The flag of the state of Illinois consists of the seal of Illinois on a white background, with the word "Illinois" underneath the seal. The present seal was adopted in 1869, the flag bearing the central elements of the seal was adopted in 1915, and the word Illinois was added to the flag in 1970. In the eagle's beak there is a banner with the state motto, "State Sovereignty, National Union." The dates on the seal, 1818 and 1868, represent the year Illinois became a state and the year in which the Great Seal was redesigned by Sharon Tyndale. Although "State Sovereignty" comes first in the motto, "State" is at the bottom and "Sovereignty" is upside-down.
Text modified from "Flag and seal of Illinois" on Wikipedia which is licensed under CC BY-SA 4.0.