Watch the Miles from Home online guitar lesson by David Blacker from Lone Wolf Blues
Here's another drop D number that makes good use out of the hypnotic drone sound created by Travis picking an alternating bass line between the low D on the 6th string and the octave on the 4th string. Like Road Weary, this piece makes use of the ambiguity between major and minor tonalities.
The major 3rd of D is just introduced briefly before the change to the IV chord in measure 4. Over the IV chord in measures 5 and 6 there is more of this tonal ambiguity with a G chord fragment that does not include the major 3rd of the scale. The fingering for the IV chord in measures 5 and 6 provides an alternative to the standard open position G7 that happens in measure 2. Varying between fingerings like this provides a nice sense of movement and freshness within a song. I recommend trying to explore new chords within drop D further up the neck. It's a great way to happen upon new sounds.
For another take on drop D check out Bob Dylan's song "Fixin' to Die".