It is associated with joy, sunshine, and tropics.  Orange represents enthusiasm, fascination, happiness, creativity, determination, attraction, success, encouragement, and stimulation.  To the human eyes, orange is seen as a very hot color, so it gives the sensation of heat.
West Virginia, Ohio, Illinois, and Indiana form the northern border  of Kentucky, along the Ohio River.
In the 18th century, the river was the primary western boundary of the young United States, and since the country's expansion westward, the Mississippi River has been widely considered a convenient if approximate dividing line between the Eastern, Southern, and Midwestern United States, and the Western United States.