Chicago, officially the City of Chicago, is the most populous city in Illinois and the third most populous city in the United States. As of the 2017 census-estimate, it has a population of 2,716,450, which makes it the most populous city in the Midwestern United States. Chicago is the county seat of Cook County, the second most populous county in the United States, and the principal city of the Chicago metropolitan area, which is often referred to as "Chicagoland." The Chicago metropolitan area, at nearly 10 million people, is the third-largest in the United States, the fourth largest in North America, and the third largest metropolitan area in the world by land area.
The Mississippi River is the largest river of the United States and the chief river of the second-largest drainage system on the North American continent, second only to the Hudson Bay drainage system. Its source is Lake Itasca in northern Minnesota and it flows generally south for 2,320 miles (3,730 km) to the Mississippi River Delta in the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 32 U.S. states and two Canadian provinces between the Rocky and Appalachian Mountains. The main stem is entirely within the United States; the total drainage basin is 1,151,000 sq mi (2,980,000 km2), of which only about one percent is in Canada. The Mississippi ranks as the fourth-longest and fifteenth-largest river by discharge in the world. The river either borders or passes through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
Springfield is the capital of the U.S. state of Illinois and the county seat of Sangamon County. The city's population of 116,250 as of the 2010 U.S. Census makes it the state's sixth most populous city. It is the largest city in central Illinois. As of 2013, the city's population was estimated to have increased to 117,006, with just over 211,700 residents living in the Springfield Metropolitan Statistical Area, which includes Sangamon County and the adjacent Menard County.
Cook County is a county in the U.S. state of Illinois. It is the second-most populous county in the United States after Los Angeles County, California. As of 2017, the population was 5,211,263. Its county seat is Chicago, the largest city in Illinois and the third-most populous city in the United States. More than 40% of all residents of Illinois live in Cook County.
Aurora, a suburb of Chicago, is a city in DuPage, Kane, Kendall, and Will counties in the U.S. state of Illinois. Located primarily in DuPage and Kane counties, it is an outer suburb of Chicago and the second most populous city in the state, and the 114th most populous city in the country. The population was 197,899 at the 2010 census, and was estimated to have increased to 200,965 by 2017.
Peoria is the county seat of Peoria County, Illinois, and the largest city on the Illinois River. Established in 1691 by the French explorer Henri de Tonti, Peoria is the oldest European settlement in Illinois, and is named after the Peoria tribe. As of the 2010 census, the city was the seventh-most populated in Illinois, with a population of 115,007. The Peoria Metropolitan Statistical Area had a population of 373,590 in 2011. Until 2018, Peoria was the global and national headquarters for Caterpillar Inc., one of the 30 companies composing the Dow Jones Industrial Average, and listed on the Fortune 100; in the latter year, the company relocated its headquarters to Deerfield, Illinois.
The Chicago metropolitan area, or Chicagoland, is the metropolitan area that includes the city of Chicago, Illinois, and its suburbs. With an estimated CSA population of 9.9 million people and an MSA population of 9.5 million people, it is the third largest metropolitan area in the United States.
The University of Illinois at Urbana–Champaign is a public research university in Illinois and the flagship institution of the University of Illinois System. Founded in 1867 as a land-grant institution, its campus is located in the twin cities of Champaign and Urbana.
The Illinois House of Representatives is the lower house of the Illinois General Assembly, the bicameral legislature of the U.S. state of Illinois. The body was created by the first Illinois Constitution adopted in 1818. The House consists of 118 representatives elected from individual legislative districts for two-year terms with no limits; redistricted every 10 years, based on the 2010 U.S. census each representative represents approximately 108,734 people.
The Illinois Senate is the upper chamber of the Illinois General Assembly, the legislative branch of the government of the state of Illinois in the United States. The body was created by the first state constitution adopted in 1818. The Illinois Senate is made up of 59 senators elected from individual legislative districts determined by population; redistricted every 10 years, based on the 2010 U.S. census each senator represents approximately 217,468 people. Under the Illinois Constitution of 1970, senators are divided into three groups, each group having a two-year term at a different part of the decade between censuses, with the rest of the decade being taken up by two four-year terms. This ensures that the Senate reflects changes made when the General Assembly redistricts itself after each census.
These are tables of congressional delegations from Illinois to the United States House of Representatives and the United States Senate.
The Illinois Central Railroad, sometimes called the Main Line of Mid-America, was a railroad in the central United States, with its primary routes connecting Chicago, Illinois, with New Orleans, Louisiana, and Mobile, Alabama. A line also connected Chicago with Sioux City, Iowa (1870). There was a significant branch to Omaha, Nebraska (1899), west of Fort Dodge, Iowa, and another branch reaching Sioux Falls, South Dakota (1877), starting from Cherokee, Iowa. The Sioux Falls branch has been abandoned in its entirety.
An incorporated town is a town that is a municipal corporation.
The Great Seal of the State of Illinois is the official emblem of the state, and signifies the official nature of a document produced by the state of Illinois. The flag of the state of Illinois consists of the seal of Illinois on a white background, with the word "Illinois" underneath the seal. The present seal was adopted in 1869, the flag bearing the central elements of the seal was adopted in 1915, and the word Illinois was added to the flag in 1970.
The following is an alphabetical list of articles related to the U.S. state of Illinois.
The following outline is provided as an overview of and topical guide to the U.S. state of Illinois:
