It all started when the Earth cooled and things called “hills” formed. I know in our topographically-challenged city that’s an alien concept, but please bear with me.
Inspired by Frank Lloyd Wright (like so many other styles), the split-level ranch is a staggered-level home, typically featuring the large living, dining & kitchen combo on the middle level; sleeping rooms tend to be on the third floor (occasionally the first), with a garage and/or basement on the first. A short set of central stairs connects all levels.
Advantages to this style include reasonable access to the foundation, plumbing and floor ducts and the ability to actually build a wide house on a hill, unfortunately they tend to be difficult to navigate for less mobile people.
You don’t see many of these homes in Dallas, but in neighborhoods with significant hills they tend to appear in clusters.