Kentucky is not one of the largest states, but its geography is diverse. It is composed of five geographic regions that attest to this diversity; the Bluegrass Region, the Cumberland Plateau, the Western Coal Field, the Pennyroyal Region, and the Jackson Purchase Region.
The Bluegrass Region lies in the northern central area of Kentucky. It has rolling meadows and sandstone “knobs” on the eastern, southern, and western edges. The Appalachian Plateau, which extends from New York to Alabama, is referred to as the Cumberland Plateau in Kentucky. This area, in the eastern portion of the state, consists of mountains, plateaus, and valleys. The Cumberland and Pine mountain ranges are found in this region of Kentucky as well as Black Mountain, the highest point in the state.
The Western Coal Field is a land of hills bordered by the Ohio River on the north, and the Pennyroyal region on the east, west, and south. It contains large coal deposits. The Pennyroyal Region stretches along the southern border of Kentucky. The southern part of this region consists of flat lands with some rolling hills. In the center is a treeless area called The Barrens. The northern section consists of rocky ridges and many underground caves and tunnels.
In the far western tip of Kentucky is the Jackson Purchase Region. Its name comes from the fact that it was purchased by Andrew Jackson in 1818 from the Chickasaw people. This area is has flood plains and low hills.
An ancient rift in the earth that runs for roughly 200 miles (320 km) along the Mississippi River valley—from Memphis, Tennesee, into Missouri and Illinois—borders on Kentucky for much of the distance. It is known as the New Madrid Fault. This rift was the site of the tremendous New Madrid earthquakes, a series of earthquakes and aftershocks that began in December 1811 and continued for at least a year. At the time, the three main earthquakes were the most powerful tremors in U.S. history; it is estimated that they registered more than 8.0 on the Richter scale. There were some 1,800 shocks and aftershocks, the strongest of which were felt as far away as Washington, D.C., and New York City. It was reported that the shocks were so strong that the Mississippi River appeared to flow backward for a few hours, as the land beneath buckled and surged upward, and Reelfoot Lake was formed, just across the border, in Tennessee.
The pennyroyal is a region of caves. Abundant waters, both surface and underground, and the limestones deposited more than 300 million years ago combined to create the area known as the Land of Ten Thousand Sinks, which includes such famous underground passages as Mammoth Cave. Designated a UNESCO World Heritage site in 1981, this vast underground cavern includes three rivers and three lakes, and its passageways cover more than 350 miles (560 km) on five levels.
In addition to the Mississippi, Ohio, and Big Sandy rivers, Kentucky has seven major drainage basins formed by streams: the Licking, Kentucky, Salt, Green, Tradewater, Cumberland, and Tennessee rivers. The longest stream completely within the state is the Green River. The Tennessee and Cumberland rivers have both been dammed to form large reservoirs. In south-central Kentucky a dam on the Cumberland has created Lake Cumberland. It is the state’s largest lake, spanning an area of more than 50,000 acres (20,000 hectares).
Kentucky enjoys a temperate climate and has plentiful rainfall. The state’s annual temperature is between 55 and 60 °F (13 and 16 °C). However, temperatures can reach above 110 °F (43 °C) and drop below –30 °F (–34 °C). Annual rainfall is about 45 inches (1,140 mm) and the yearly growing season lasts about 170 to 210 days, depending on location. Thunderstorms are frequent and often cause flooding in eastern Kentucky. The southern and lowland regions are slightly warmer than the uplands. The record high temperature for the state was 114°F (46°C), reached in Greensburg on 28 July 1930; the record low was –37°F (–40°C), recorded in Shelbyville on 19 January 1994.
