Illinois is the 21st state of the United States of America, admitted to the Union on December 3, 1818.

Illinois was little more than a vast wilderness 200 years ago. Since entering the Union in the early 19th century, the economy of Illinois has gradually expanded and today, the state is one of the most productive agricultural and industrial centers, and its economic influence now extends far beyond the MidWest.

Flanked by the Mississippi River on the West and by a short stretch of Lake Michigan on the NorthEast, the state is largely an area of flat or gently rolling plains that were once covered by tall luxuriant prairie grasses. The grasslands have long since been cleared for raising crops, but the state still retains its nickname, the Prairie State.

Much of the land is tidily laid out in the checkerboard pattern so typical of the MidWest. Large prosperous farms specialize in raising grain and livestock on the rich prairie soils.

Tall grain elevators, church spires, and an occasional grove of trees are the most conspicuous landmarks; and machine sheds, fields of corn and soybeans, and hogs in feedlots are the most common sights across the farmlands.

Rural Illinois does not lack physical and agricultural diversity. It has hill lands and a national forest in the South, cotton fields on the fertile alluvial lands in the extreme South, scenic bluffs along the Mississippi, and hillside dairy farms in the NorthWest.

In addition, rural Illinois is far from being isolated from urban Illinois. The state is covered by a dense network of railroads, highways, waterways, and air routes, most of which converge on the great metropolis of Chicago.

The third largest city in the United States, Chicago dominates the industrial, financial, and social life of the state. In some ways, Chicago stands apart from the rest of the state. To many Chicagoans, Illinois consists of two sections: Chicago and "downstate".

Other Illinois cities, such as Peoria, Rockford, and Decatur, tend to be overshadowed by Chicago. Nevertheless, these smaller communities manage to retain their distinctive characteristics.

Perhaps the most famous is the state capital, Springfield, which President Abraham Lincoln often referred to as his home.

The national fame of Springfield, New Salem, and other places in Illinois that are associated with Lincoln are reflected in the official state slogan, Land of Lincoln.

The state is named for the Illinois, or Illini, a confederation of Native Americans of various tribes who inhabited Illinois and other sections of the MidWest at the time the first French explorers entered the region. The name Illinois is said to have been a French version of the Illini word for themselves, Illiniwek.

Chicago, the seat of Cook County, is the principal city of inland North America. The city is one of the leading commercial, industrial and transportation centers in the United States. The Chicago Metropolitan Statistical Area includes adjacent counties in Wisconsin and Indiana.

Rockford, the seat of Winnebago County in Northern Illinois, is primarily an industrial center that is noted for the manufacture of machine tools.

Unlike many of the larger of the state’s cities, Aurora, a residential and industrial satellite of Chicago, gained population during the 1980s and 1990s.

Other major cities in Illinois include

• Naperville, in DuPage and Will counties, a Chicago suburb in the Illinois technology and research corridor;
• Peoria, the seat of Peoria County, a manufacturing center on the Illinois River in the central part of the state;
• Springfield, the seat of Sangamon County in central Illinois and the state capital, noted for its associations with Abraham Lincoln;
• Joliet, the seat of Will County;
• Elgin, in Kane and Cook Counties;
• Decatur, the seat of Macon County, a trade and industrial center in an agricultural area of central Illinois;
• Evanston, on Lake Michigan in Cook County, a residential suburb of Chicago and the home of NorthWestern University;
• Belleville, the seat of St. Clair County; and
• East Saint Louis, on the East bank of the Mississippi River in St. Clair County in SouthWestern Illinois, opposite St. Louis, Missouri.