I was surprised to see Las Vegas as such a tiny blip, before remembering its history is still very recent. Founded in 1905, incorporated in 1911 (and was still decades away from its boom).
Las Vegas as a city wasn't really feasible until after the completion of the Hoover Dam and Lake Mead in 1936 about 30 miles away. You can't have a city without water.
https://en.wikipedia.org/wiki/Las_Vegas