Illinois is the 5th most populous of the 50 United States, and is often used as a microcosm for the entire country. With financially and culturally strong Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal, timber, and petroleum in the south, Illinois has a very broad and diverse economic base. Illinois is a major transportation hub. The Port of Chicago connects the state to other global ports from the Great Lakes, via the Saint Lawrence Seaway, to the Atlantic Ocean; as well as the Great Lakes to the Mississippi River, via the Illinois River. For decades, O'Hare International Airport has 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 politics. Although the state's largest population center is in and around Chicago, originally the state's European population grew first in the west, with French Canadians who settled along the Mississippi River. After the American Revolutionary War established the United States, American settlers began arriving from Kentucky in the 1810s via the Ohio River, and the population grew from south to north. In 1818, Illinois achieved statehood. After construction of the Erie Canal increased traffic and trade through the Great Lakes, Chicago was founded in the 1830s on the banks of the Chicago River, at one of the natural harbors on southern Lake Michigan. John Deere's invention of the self-scouring steel plow turned Illinois' rich prairie into some of the world's most productive and valuable farmlands, attracting immigrant farmers from Germany and Sweden. Railroads carried immigrants to new homes, as well as being used to ship their commodity crops out to markets. By 1900, the growth of industrial jobs in the northern cities and coal mining in the central and southern areas attracted immigrants from Eastern and Southern Europe. Illinois was an important manufacturing center during both world wars. The Great Migration from the South established a large community of African Americans in Chicago, who created the city's famous jazz and blues cultures. Illinois has historically and still plays a strong role on the nation's political scene. Three U.S. presidents have been elected while living in Illinois: Abraham Lincoln, Ulysses S. Grant, and Barack Obama. Additionally, President Ronald Reagan, whose political career was based in California, was born and raised in Illinois, and former First Lady and Secretary of State Hillary Rodham Clinton was born and raised in Illinois. The country's first Black female Senator, Carol Mosley Braun was born, raised, and elected to the Senate from Illinois. And current Chicago mayor Rahm Emanuel served as White House Chief of Staff for several years before resigning to run for mayor of Chicago. Today, Illinois honors Abraham Lincoln with its official state slogan, Land of Lincoln, which has been displayed on its license plates since 1954. The Abraham Lincoln Presidential Library and Museum is located in Springfield, while the Barack Obama Presidential Library is expected to be located in Chicago.