Phase 1 of the project reported raw statistics on upward mobility for each commuting zone (CZ) in the United States. The differences are driven by a combination of differences in the types of families living in each area (e.g., differences in demographic makup and wealth) as well as causal effects of each area on a given child. In phase 2, we isolate the causal effects of each county and CZ in the U.S. by studying families that move across areas. The causal effect estimates can be interpreted as the answer to the question, “How would my child do on average if he/she were to grow up in a different county?”.
Although the causal effects estimated in phase 2 are highly correlated with the raw statistics on upward mobility reported in phase 1, there are several differences driven by variation in the types of people who live in each area. For example, the New York area ranked highly on rates of upward mobility in phase 1, but its causal effect on upward mobility for a given child is not much better than other cities such as Washington D.C. New York has high levels of mobility on average because it has many immigrants, whose children tend to have high rates of mobility irrespective of where they grow up. But this does not mean that moving to New York will improve a given child’s chances of moving up.