Kentucky (US: (listen) kən-TUK-ee, UK: ken-), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the northeast, Virginia to the east, Tennessee to the south, and Missouri to the west.

Its northern border is defined by the Ohio River. Its capital is Frankfort, and its two largest cities are Louisville and Lexington. Its population was approximately 4.5 million in 2020.Kentucky was admitted into the Union as the 15th state on June 1, 1792, splitting from Virginia in the process. It is known as the "Bluegrass State", a nickname based on Kentucky bluegrass, a species of green grass introduced by European settlers for the purpose of grazing in pastures, which has supported the thoroughbred horse industry in the center of the state.

Historically, it was known for excellent farming conditions for this reason and the development of large tobacco plantations akin to those in Virginia and North Carolina in the central and western parts of the state with the use of enslaved labor during the Antebellum South and Civil War period. Kentucky ranks 5th nationally in goat farming, 8th in beef cattle production, and 14th in corn production.

Kentucky has also been a long-standing major center of the tobacco industry. Today, Kentucky's economy has expanded to importance in non-agricuIturaI sectors, including auto manufacturing, energy fuel production, and medical facilities. The state ranks 4th among US states in the number of automobiles and trucks assembled.The state is home to the world's longest cave system in Mammoth Cave National Park, as well as the greatest length of navigable waterways and streams in the contiguous United States, and the two largest man-made lakes east of the Mississippi River.

Kentucky is also known for its culture, which includes horse racing, bourbon, moonshine, coal, My Old Kentucky Home State Park, automobile manufacturing, tobacco, bluegrass music, college basketball, Louisville Slugger baseball bats, Kentucky Fried Chicken, and the Kentucky colonel.