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Louisville is the most populous city in Kentucky and the 27th-largest in the United States, uniquely sharing its borders with Jefferson County since the 2003 city-county merger that created Louisville Metro (population ~783,000). Founded in 1778 by George Rogers Clark and named after King Louis XVI of France, the city grew as a vital portage point around the Falls of the Ohio River and later became the birthplace of the massive Louisville and Nashville Railroad. Today, it is famous for iconic institutions and figures such as the Kentucky Derby, Muhammad Ali, Kentucky Fried Chicken, the University of Louisville, and Louisville Slugger baseball bats, while also hosting Fortune 500 headquarters for Humana and Yum! Brands. The city also operates the Louisville Muhammad Ali International Airport, which serves as the global hub for UPS. Adding to its unique culture, the pronunciation of "Louisville" is hotly debated—locals favor "LOO-uh-vəl" or "LUUV-əl," while outsiders often say "LOO-ee-vil," and the rare "LOO-iss-vil" is widely considered the only unacceptable option.