The city of Chicago, also called "The Windy City", "The Second City", "Chi-Town", "Chi-City", "Hog Butcher for the World", "The City That Works", "and others found at List of nicknames for Chicago" was settled in 1770s and encompasses the following counties: Cook, DuPage. Chicago's government type is Mayor–council. It is comprised of the Mayor, who is currently Rahm Emanuel (D).
Chicago encompasses land area: 227.2 sq mi (588 km2), water area: 6.9 sq mi (18 km2) 3.0%. The elevation is 597 ft (182 m) above sea level. According to the 2010 United States Census, the local population is 2,707,120. This equates to a population density of 11,864.4/sq mi (4,447.4/km2). Anyone living in the city is commonly known as a "Chicagoan". The local time zone is CST (UTC−06:00).
Local area codes are 312, 773, 872. Additional information and the official website of the city is found at cityofchicago.org.