I wonder if there is a measurement for what i see in MSAs like NJ. The mix of wealthy and poor in the same town or same street even. So many people with so mu

I wonder if there is a measurement for what i see in MSAs like NJ. The mix of wealthy and poor in the same town or same street even. So many people with so much money are significantly upgrading houses or outright purchasing for their children (or huge down payment) that neighborhoods have 1.5$m homes across from $125k homes. It used to be just about everyone in a neighborhood could afford to buy each other's house.