According to Lindsey Starnes, the term country music gained popularity in the 1940s in preference to the earlier term hillbilly music; it came to encompass Western music, which evolved parallel to hillbilly music from similar roots, in the mid-20th century. In 2009 in the United States, country music was the most listened to rush hour radio genre during the evening commute, and second most popular in the morning commute.
The term country music is used today to describe many styles and subgenres. The origins of country music are found in the folk music of working class Americans, who blended popular songs, Irish and Celtic fiddle tunes, traditional English ballads, cowboy songs, and the musical traditions of various groups of European immigrants.
Immigrants to the southern Appalachian Mountains of eastern North America brought the music and instruments of Europe along with them for nearly 300 years. Country music was "introduced to the world as a Southern phenomenon."