Although folk festival favorites, the New Lost City Ramblers specialized in playing, often note-for-note, the works of early rural (country) artists such as the Binkley Brothers, the Arthur Smith Trio and "Uncle Dave" Macon.

I think the evolution was: folk > hillbilly > Country & Western > Country. The latter is almost purely commercial and a type of pupular music, not to be confused with Pop, which evolved from the old Tin Pan Alley writers.