Not as much as you think. Here’s some trivia for you: which urban area is more densely populated, NYC or LA?

The answer is actually LA. Everyone imagines Manhattan or Brooklyn when they think of NYC but actually a huge part of the city in an economic and cultural sense consists of low density suburbs, enough so that it brings the average below famously sprawling LA. Allowing more density in these neighborhoods would likely help reduce the cost in the core of the city. Some neighborhoods might remain expensive—if you’re competing with investment bankers who will pay any price to be in walking distance of Wall St, adding more housing in other boroughs or satellite communities won’t help with that. But it could make a dramatic difference on overall cost of living in NYC. It’s only expensive because way more people want to live in a relatively small urban core than can fit there.

The same solutions can solve or greatly mitigate these problems in virtually every American city. This is because even large, older cities that predate the horrific car-centric development of the post-war era are surrounded by huge swathes of this type of development.