Dolly Parton and Steve Earle would seem to have almost nothing in common. One was born and raised in poverty, but became a pop culture superstar. The other has lived defiantly outside the mainstream and became a dogged champion of the marginalized. Theyâ€™re also two of the most prolific and influential songwriters working in the American roots tradition. This month on the Enright Files, how artists as different as Steve Earle and Dolly Parton capture the essence of American roots music and speak to the cultural and political currents of the past few decades in the United States.