Here's the link for the King County assessment.
Location matters – enormously. If you’re poor and live in the Seattle area, it’s better to be in Snohomish County than in Pierce County or Skagit County. Not only that, the younger you are when you move to Snohomish, the better you will do on average. Children who move at earlier ages are less likely to become single parents, more likely to go to college and more likely to earn more.
These findings, particularly those that show how much each additional year matters, are from a new study by Raj Chetty and Nathaniel Hendren that has huge consequences on how we think about poverty and mobility in the United States. The pair, economists at Harvard, have long been known for their work on income mobility, but the latest findings go further. Now, the researchers are no longer confined to talking about which counties merely correlate well with income mobility; new data suggests some places actually cause it.
Consider King County, Wash., our best guess for where you might be reading this article.
It’s among the best counties in the U.S. in helping poor children up the income ladder. It ranks 2,013th out of 2,478 counties, better than about 81 percent of counties. It ranks better for poor children than it does for rich children.