There is the concept of eminent domain which lets the government force-purchase land for this purpose. However it's typically only done in cities or where the g

There is the concept of eminent domain which lets the government force-purchase land for this purpose. However it's typically only done in cities or where the geography / geology requires it. Out in California's central valley where it is flat as far as the eye can see, it's sometimes better politically to do a curve to follow edges of property lines than to piss off some big wig ranchers.