The explanation of the word is long and complex but this is the short version.

I think: drifter. And … shiftless.

But really drift is just dirt and rocks pushed ahead of a glacier. It happened for four glaciations at least and the big ice got as far as Cairo down in Illinois.

But for some reason no one really understands, up in this far northeast corner of Iowa, the area was spared from the dirty rocky inundation.

It was and is

Driftless.