system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does New York have three big international airports?

Wouldnt one be enough?
gpt
Out of necessity. There are physical limitations on how many planes can land and take off in an hour on a strip. There are physical limitations on how many strips you can build on a dedicated space. There are minimum lengths to respect for a strip. This means that there is a limited number of flights to schedule on a specific airport. Also the airport has a limited number of people that can move around in it.

Given that, the other side is demand. NYC and its urban area has grown a lot these past 50 years. Also plane travel has increased exponentially.

Now the 2 have to meet. If the demand is too high for the supply of flights, you can act on the following parameters:

1 - Make planes land and take off closer to each other - Electronics help do that, but you will reach a physical limit. A plane creates turbulence and the one just behind can be subjected to too much stress (there was a plane crash 20 years ago over Jamaica, NY that showed this).

2 - Make bigger planes to transport more people - The 747 has gotten a bit bigger, and the ~~A480~~ A380 is humongous. But airport arrival areas are too small for the ~~A480~~ A380 and need sizable modifications. Now this increases capacity by 20 or 30% but not every airport or airline will buy a ~~A480~~ A380.

3 - Build another airport, in a different location. In NYC, this means 3 major airports.