America is new. Even in the 90s boulder was largely empty, competition for land was low, so land was cheap. As people spread to newer cities and gained wealth they bid up the price on land.
Still plenty of cheap land in CO, but they made drilling a well a nightmare in many cases. So people wanting to use cheap land either have to haul water or do some kind of low-key wildcat drilling.
> Even in the 90s boulder was largely empty
Uh, no it wasn't? I was living there and continued living there for the next 30 years. It always felt about as dense to me as it did back then.