From elevations of about 2,000 ft (610 m) on the Cumberland Plateau in the southeast, where Black Mt. (4,145 ft/1,263 m) marks the state's highest point, Kentucky slopes to elevations of less than 800 ft (244 m) along the western rim. The narrow valleys and sharp ridges of the mountain region are noted for forests of giant hardwoods and scented pine and for springtime blooms of laurel, magnolia, rhododendron, and dogwood. Unfortunately, these forests have suffered from the effects of acid rain. To the west, the plateau breaks in a series of escarpments, bordering a narrow plains region interrupted by many single conical peaks called knobs. Surrounded by the knobs region on the south, west, and east and extending as far west as Louisville is the bluegrass country, the heart and trademark of the state.
To the south and west lie the rolling plains and rocky hillsides of the Pennyroyal, a region that takes its name from a species of mint that grows abundantly in the area. There, underground streams have washed through limestone to form miles of subterranean passages, some of the notable ones being in Mammoth Cave National Park.
Northwest Kentucky is generally rough, rolling terrain, with scattered but important coal deposits. The isolated far-western region, bounded by the Mississippi, Ohio, and Tennessee rivers, is referred to as the Purchase, or Jackson Purchase (for Andrew Jackson, who was a prominent member of the commission that bought it from the Chickasaw in 1818). Consisting of floodplains and rolling uplands, it is among the largest migratory bird flyways in the United States.
Rivers are an important feature of Kentucky geography. The Ohio River forms the entire northern boundary of the state, flowing generally SW below Covington, until it joins the Mississippi River W of Paducah. At the southwest tip of the state about 5 sq mi (13 sq km) of Kentucky territory, created by a double hairpin turn in the Mississippi River, protrudes N from Tennessee into Missouri and is entirely separate from the rest of the state. In the east, the Big Sandy River and its tributary, the Tug Fork, form the boundary with West Virginia. Many rapid creeks in the Cumberland Mountains feed the Kentucky, the Cumberland, and the Licking rivers, which, together with the Tennessee and the Ohio, are the chief rivers of the state. The Kentucky Dam on the Tennessee River near Paducah, is a major part of the Tennessee Valley Authority system.
Kentucky's climate is generally mild, with few extremes of heat and cold. Frankfort is the capital, Louisville and Lexington the largest cities. Little remains of Kentucky's great forests that once spread over three quarters of the state and were renowned for their size and density. Tourist attractions include the famous Kentucky Derby at Churchill Downs in Louisville and the celebrated horse farms surrounding Lexington in the heart of the bluegrass region. The Abraham Lincoln Birthplace National Historic Site and Cumberland Gap National Historic Park are historic landmarks. At Fort Knox is the U.S. Depository.