The origin of the Sod House on the Nebraska plains as a unique American invention as opposed to the Scandinavian log house or European barns. They ranged from very simple, primitive houses to two story houses with roofs and chimneys. they were known to be air tight and sound proof more than timber houses. there are a couple dozen sod houses that are still occupied on the plains. More are open to the public as historical tours. The last sod house was built in 1940.