Steve Earle is, if not the most important country musician
right now, he is definitely the most thoughtful. His lyrics
reflect his tangled past of heroin addiction
time and five marriages
He at one point in the late eighties was the golden child of Nashville, but refusing to stay in the country genre, he released the much more rock oriented Copperhead Road, which many people in country music considered a giant fuck you, because some were hoping he would bring rock and country closer together.
He also has claimed to be a marxist on occasion, and his lyrics sometimes back up that claim. As far as marxist musicians go he's a welcome alternative to moronic music of Rage Against the Machine.
His latest release Transcendental Blues is a blend of the populist rock of 1997's El Corazon and the blue grass of 1999's The Mountain. He also is teaching songwriting in Chicago and has kicked his heroin habit. I saw him this past summer at the Pittsburgh Blues Festival and would suggest that you see him play if he is in your area.