Illinois is a state in the Midwestern and Great Lakes regions of the United States. It has the fifth largest gross domestic product (GDP),
the sixth largest population, and the 25th largest land area of all U.S. states. Illinois has been noted as a microcosm of the entire United States. With Chicago in northeastern Illinois, small industrial cities and immense agricultural productivity in the north and center of the state, and natural resources such as coal, timber, and petroleum in the south, Illinois has a diverse economic base, and is a major transportation hub. Chicagoland, Chicago's metropolitan area, encompasses about 65% of the state's population. The Port of Chicago connects the state to international ports via two main routes: from the Great Lakes, via the Saint Lawrence Seaway, to the Atlantic Ocean and from the Great Lakes to the Mississippi River, via the Illinois River, through the Illinois Waterway. The Mississippi River, the Ohio River, and the Wabash River form parts of the boundaries of Illinois. For decades, Chicago's O'Hare International Airport has been ranked as one of the world's busiest airports. Illinois has long had a reputation as a bellwether both in social and cultural terms and, through the 1980s, in politics.