When it comes to the demographics of the state of Illinois, the largest city is Chicago. In fact, it is the third-most-populous city in the U.S. In the 2010 census, 65.6 percent of the population of Illinois lived in one of the metro areas that surround Chicago. Other major cities include Joliet and Springfield. Historically, Peoria was the state's second largest city.
The state's political system is modeled after that of Kentucky, with three branches: the executive branch (the Governor), the legislative branch (the Legislature), and the judicial branch (the governor and the Attorney General). The General Assembly consists of 118 members of the House of Representatives and 59 members of the Senate. The state's highest court, the Illinois Supreme Court, oversees the state's lower circuit and appellate courts.
At the turn of the 20th century, Illinois' population was just over 5 million. This rapid growth attracted people from neighboring states. In fact, whites made up 98% of the state's population. Continued immigration from southern and eastern Europe, and the African-American Great Migration increased the state's population. Ultimately, Illinois became the most populous state in the union. So, it's easy to see why people move to Illinois for the lifestyle.
The Midwest region of Illinois consists of the Quad Cities. The Quad Cities region is located on the Mississippi River and has a population of 381,342 as of 2011.