Western Music
During the 1930s and 1940s Cowboy songs, or "Western music", which had been recorded since the 1920s, were popularized by films made in Hollywood. Some of the popular singing cowboys from the era were, Gene Autry, the Sons of the Pioneers, and Roy Rogers.
Another "country" musician from the Lower Great Plains who had become very popular as the leader of a “hot string band”, and who also appeared in Hollywood Westerns was Bob Wills. His mix of "country" and jazz, which started out as dance hall music, would become known as Western Swing.
Spade Cooley and Tex Williams also had very popular bands and appeared in films. At the height of its popularity, Western Swing rivaled the popularity of other big band jazz.
Country musicians began recording boogie in 1939, shortly after it had been played at Carnegie Hall, when Johnny Barfield recorded "Boogie Woogie". The trickle of what was initially called Hillbilly Boogie, or Okie Boogie (later to be renamed Country Boogie), became a flood beginning around late 1945.
One notable country boogie from this period was the Delmore Brothers' "Freight Train Boogie", considered to be part of the combined evolution of country music and blues towards rockabilly.
In 1948 Arthur "Guitar Boogie" Smith achieved Top 10 US country chart success with his MGM Records recordings of "Guitar Boogie" and "Banjo Boogie", with the former crossing over to the US pop charts.
Other country boogie artists include Merrill Moore, and Tennessee Ernie Ford. The Hillbilly Boogie period lasted into the 1950s, and remains as one of many subgenres of country into the twenty first century.
By the end of World War II "mountaineer" string band music known as Bluegrass had emerged when Bill Monroe joined with Lester Flatt and Earl Scruggs, led by Roy Acuff at the Grand Ole Opry in Nashville, Tennessee.
Gospel music, too, remained a popular component of country music.
"Honky tonk" songs associated with Texas and California barrooms, performed by the likes of Ernest Tubb, Ted Daffin, Floyd Tillman, and the Maddox Brothers and Rose, and later by Hank Williams, would later be called "traditional" country.
In this post WWII period "country" music was called "folk" in the trades, and "hillbilly" within the industry.
Many musicians performed and recorded songs in any number of styles. Moon Mullican played Western Swing, but also recorded songs that can be called rockabilly.
Bill Haley sang cowboy songs, and was at one time a cowboy yodeler. Haley became most famous as an early player of rock n roll.
Lefty Frizzell played in honky tonks Jimmie Rodgers-stylings to his environment, thus creating a sound that was very much his own.
From Wikipedia