For example, for a town of 5,000 people, if you bring in 1000 more people, what is going to happen?
The result: all rentals will be full, rent goes up quickly, hotels will be full.
There will be service stations built up and permanent employment after the pipelines are built up.
The same scale is: New York has 7 million people right now, and suddently there are 1.4 new comers coming to town...