These artifacts indicate that Cahokia was truly an urban center, with clustered housing, markets, and specialists in toolmaking, hide dressing, potting, jewelry making, shell engraving, weaving and salt making.
The civilization vanished in the 15th century for unknown reasons, but historians and archeologists have speculated that the people depleted the area of resources.
The Mississippi River, the Ohio River, and the Wabash River form parts of the boundaries of Illinois.
For decades, O'Hare International Airport has been ranked as one of the world's busiest airports.
It is 100 feet (30 m) high, 951 feet (290 m) long, 836 feet (255 m) wide and covers 13.8 acres (5.6 ha).), and been as much as 50 feet (15 m) high, making its peak 150 feet (46 m) above the level of the plaza.
The finely crafted ornaments and tools recovered by archaeologists at Cahokia include elaborate ceramics, finely sculptured stonework, carefully embossed and engraved copper and mica sheets, and one funeral blanket for an important chief fashioned from 20,000 shell beads.
French explorers Jacques Marquette and Louis Jolliet explored the Illinois River in 1673.
Illinois was an important manufacturing center during both world wars.John Deere's invention of the self-scouring steel plow turned Illinois's rich prairie into some of the world's most productive and valuable farmland, attracting immigrant farmers from Germany and Sweden.The Illinois and Michigan Canal (1848) made transportation between the Great Lakes and the Mississippi River valley faster and cheaper.Illinois has long had a reputation as a bellwether both in social and cultural terms and politics.The capital of Illinois is Springfield in central Illinois.