why do people/or locations like Oklahoma and general out west do not have basements?

[jeff47]

5. Frost. Or lack thereof.

There is a "frost line". This is the depth to which the ground freezes in winter. Frozen ground expands, and can push the foundation of a house right out of the ground. The foundation of a house has to be built deeper than the frost line, so that the foundation stays where it's supposed to be.

The frost line in New England is at about 8 feet. If you already have to dig down 8 feet for the foundation, digging a basement doesn't add much of an expense. So virtually every house in New England has a basement.

The frost line in Los Angeles is at 0 feet - it never freezes. So foundations were traditionally only about 2 feet deep. So digging down 8 to 10 feet to put in a basement adds a lot of cost to a house. (In the past few decades, foundations in Los Angeles have gotten deeper and more complex to handle earthquakes, but they're still only around 4 feet deep). As a result, virtually no house in Los Angeles has a basement.

The frost line in Oklahoma City is about 18", so foundations should be around 3 feet deep. So digging a basement would add a lot of cost.