Chicago is among the largest cities in the U.S. Famed for its bold architecture, the population of the city is rank 3rd largest city in USA. Chicago had the third largest gross metropolitan product in the United States at US $571 billion. With over 2.7 million residents, it is the most populous city in the state of Illinois and the Midwest. Chicago is the third most populous city in the United States. The city is an international hub for finance, commerce, industry, technology, telecommunications, and transportation; with O’Hare, International Airport being the busiest airport in the world. Chicago is a major transportation hub in the United States. It is an important component in global distribution, as it is the third-largest inter-modal port in the world after Hong Kong and Singapore.
Chicago has been a world center of higher education and research with several universities that are in the city proper or in the immediate environs. Chicago has the third-largest gross metropolitan product in the United States about $630.3 billion according to 2014–2016 estimates. The city has also been rated as having the most balanced economy in the United States, due to its high level of diversification.
Chicago was named the fourth-most important business center in the world in the MasterCard Worldwide Centers of Commerce Index. Additionally, the Chicago metropolitan area recorded the greatest number of new or expanded corporate facilities in the United States.