&gt; but Manhattan could have significantly higher population density without overwhelming the infrastructure.<p>This is not really true, mostly based on the transportation infrastructure.  Manhattan is absolutely not ready to move more people around per day.  Both train and car traffic is rising sharply and neither system are scaling particularly gracefully.  I&#x27;m not informed about water treatment, police&#x2F;fire services etc., but I&#x27;d be surprised to hear that they are operating with a lot of room for growth.  Hospitals are a mess.<p>Have you ever played any Sim City at all?  Jeez this is basic stuff :)