Simplistically, you can date what we think of as Country (or C&W) Music from approximately Ernest Tubb and the year 1940.

After the first flush of oldtime music (the original country music made by people like the Carter Family, Jimmy Rodgers, Charlie Poole, etc.) there were plenty of country musicians who developed a distinct commercial sound. For instance, top sellers like Patsy Montana. Gene Autry emerged from his imitation Jimmie Rodgers period and went on to record newly written music whose flavor was distinct from folk roots. For that matter so had Rodgers.

Western Swing developed in the 1930s, mingling hot jazz and country, tremendously influential in the midwest and southwest. People like Bob Atcher recorded early country stuff. The names are endless.

But the big divide came with World War II. A lot of southern boys went to basic training camps in the north, northerners in the south. They all mingled both stateside and overseas. Radio picked up sounds they liked.

By the time the war was over, the C&W industry was well on its way, developing in centers like Nashville. Old time country music, which was strongly linked to folk as well as older popular music from the 19th-early 20th century, had essentially collapsed. The new sounds represented by people like Ernest Tubb -- think "Walkin' the Floor Over You" and a million honkytonk songs -- took over. Typical of the sound were hot fiddles, steel guitar, occasional accordion, and a hot downbeat anchored by string bass. Vocals and songs were equally sophisticated with a new genre self-consciousness by contrast with what had gone before.

The Carter Family disbanded, Jimmie Rodgers had died, Uncle Dave Macon had been homogenized by the smoother sounds of the Delmore Brothers in the 1930s. Radio itself demanded and created a warm smooth sound.

Artists like Bill Monroe were able to make the transition from one to the other; but very few others did. The war, and the spread of radio with its live shows and recorded music on transcription disks, marked the changing of an era. By 1942, it is generally agreed, the end had come for indigenous folk sounds as a commercially recorded genre.

Thereafter folk mutated and reemerged in the 1950s, but as an urban phenomenon. There would never be another genuine traditional music industry. It had been a fluke in the first place, a novelty that sold well in the south till its back was broken by the Depression.

Quite a story here, if you dig further. See Bill Malone's books, Robert Shelton's Country Music Story is an oldie but still good. If you check Amazon for "old time music," "early country music," etc. you'll find quite a number of books on the subject. The net also has some good resources ripe for the googling.

Enjoy,

Bob