Illinois constitutes the 21st state of the United States, located in the former Northwest Territory. Its name was given by the state's French explorers after the indigenous Illiniwek people, a consortium of Algonquin tribes that thrived in the area. The word Illiniwek means simply "the people". Its capital of Illinois is Springfield while its largest city is Chicago, along the waterfront of Lake Michigan. Most of the state's population resides in Chicago and its suburbs. The U.S. postal abbreviation for the state is IL.