Why in the world would the average working family have children in NYC? This is NOT the place to raise kids. The costs for everything in NYC is relative to the fact that YOU LIVE IN NYC.
Planning to have a child if you live in NYC is key. I worked with a lawyer whose wife stayed at home to tend to her son. It wasn't worth it for her to go back to work. One income until their son was time to go to school. Plan. Wait. Think.
