Southern California home of slab homes and crawl spaces. One home on my block has a cellar that was dug by the original 1941 owner. My Aunt and Uncles home in Shell Knob MO. had a cellar and an additonal 6 x 12 tornado room into the hillside thru the cellar. Also served as a hidden vault. They lived in what was called Tornado alley, although I can't recall any tornadoes hitting there