But Nebraska was not always a bed of roses. When the first settlers arrived, they found a harsh, unforgiving place, a vast treeless expanse of barren, drought-parched soil. And so, summoning up the dynamic pioneer spirit of hope and steely determination, they left. But a few of them remained and built sod houses, which are actually made of dirt. Think about that. You can't clean a sod house, because it would be gone. The early settlers had a hell of a time getting this through to their children. "You kids stop tracking dirt out of the house!" they'd yell.
Dave Barry's Only Travel Guide You'll Ever Need (1991)