I'm not sure where this notion that cities run out of space comes from. We've always had high land utilization in cities. But the cities still grow, they grow b

I'm not sure where this notion that cities run out of space comes from. We've always had high land utilization in cities. But the cities still grow, they grow by replacing low density residences with higher density residences. So forth and so forth. If a city can't grow by building up then that's most likely a zoning issue.