A couple of points regarding the time period / location...
- Nolan has confirmed that he show takes place in the 21st Century.
- If the technology exists to create life-like humanoid robots, the technology can just as easily exist to design/engineer the terrain for, say, a 100 square mile area. I can't find the exact quote but I'm fairly certain Ford says something along the lines that he designed every square inch of the park himself. Whether that means making a few terrain alterations to somewhere in Utah, or completely "building" every structure, trail and grain of sand over acres and acres Florida or an on an island or wherever, it's irrelevant. Simply because we can't possibly know what kind of land altering/building technology exists in this time period. For all we know Iowa went to hell for some reason or another and the Delos company bought it from the government and changed it into Westworld. Point is, we can't make assumptions based on the way our world is today.