I think Illinois largest city is Chicago Chicago
Auckland is the largest city in New Zealand, with close to one million people.
Illinois is not a city. It is a state. Based on population, Illinois is the 5th largest U.S. state.
Chicago is the largest city in Illinois and the third most populous city in the United States, with an estimated population of 2,704,958 as of July 1, 2016 per the U.S. Census Bureau.
Most probably, one of the 21 million people living in such city.
Auckland
Auckland
The largest city in Georgia is Tbilisi, with a population of just over one million people. The largest city in the U.S. state of Georgia is Atlanta, with a population of just over half a million people.
The Illinois city with the largest population is Chicago with approx. 2.8 million people. Also, Chicago is the 3rd largest city in the US by population, behind New York City & Los Angeles. See related links for more info.
Rome was the first city to have one million inhabitants, and this occurred in 133 BC. The second city to reach the one million mark was Alexandria, Egypt in 30 BC.
Mexico City is the economic, political and cultural capital of the country of Mexico. It has 8 million people within the city proper, but the metropolitan area is home to more than 21 million people.
Melbourne, Sydney, Brisbane, Adelaide, Perth.