|Kentucky is among the four commonwealth states of the US. It joined the Union in 1792 to become the 15th state, after ceasing to be a part of Virginia. The commonwealth of Kentucky has a total area of 40,409 square miles, which makes it the 37th largest state of the country in size. In terms of population, it ranks 26th with more than four million residents living across the state. Kentucky is located in the east central part of the nation with a neighborhood of as many as seven states. These includes West Virginia, Virginia, Tennessee, Missouri, Illinois, Indiana and Ohio. Its northern border is defined by Ohio river, which separates it from the state of Ohio. Similarly, Mississippi river towards its western border separates it from Missouri. Nicknamed as the "Bluegrass State", Kentucky has an abundance of bluegrass in lawns and pastures spread throughout the state. It has a plentiful of other resources also, such as navigable waterways, streams and man-made lakes, and world's longest cave system is found here. No other place in the United States has more per capita number of turkey and deer than the commonwealth of Kentucky. Louisville is the largest city while Frankfort is the capital of the state.