Yes it is.
Illinois was admitted into the Union in 1818.
Yes, Illinois is in the United States of America on the continent of North America.
As a part of Illinois it became a part of the US on 3 December 1818.
It is a city within the US State of Illinois.
The same year as the rest of Illinois, in 1818.
Illinois is located in the Midwest Region of the United States.
Illinois is located in the Midwest Region of the United States.
Chicago is located in Illinois.
All of these are states in the US.
Illinois was admitted to the Union on December 3, 1818 becoming the 21st state to join the union.
Chicago is part of Cook County which is part of the State of Illinois which is part of the United States of America. So, Chicago isn't far from the US because it is IN the US.
In the US Supreme Court it was reversed in part and affirmed in part. For decision see below:
Illinois was acquired from Britain as part of the treaty ending the Revolutionary War which was before the Louisiana Purchase. The French had earlier ceded Illinois to the British with the treaty that ended the French and Indian War.
"Il" is the postal abbreviation for "Illinois" in the US, and the US is located in the Western Hemisphere.