Growing up in Salt Lake City from birth increases the adult household income of a child raised in a low-income family by 10.4% (measured at the age of 26), compared to the average commuting zone (CZ). By contrast, growing up in Philadelphia decreases a poor child’s adult income by 1.8%. . . .Salt Lake City is a particularly good for girls to grow up in, in terms of the impact on their future adult household income (Fig. 2):

[Figure 2]

. . . .But when it comes to individual incomes, the story changes—especially for Salt Lake City. Growing up in Salt Lake City slightly reduces the individual adult incomes of low-income children at age 26 (by 0.6%).

. . . .So, the inevitable question arises: How can Salt Lake City be so good for household income mobility when it is not good at all for individual income mobility? Simple: more households in which individual incomes are shared. Growing up in Salt Lake City hugely increases the chances of being married in adulthood. In fact, no other city comes even close in terms of causal impact on marriage (Fig. 5):

[Figure 5]

Salt Lake City is an outlier here, for reasons related to the specific culture of the city. Most importantly, about half the population belongs to the Church of Jesus Christ of Latter-day Saints (informally referred to as the Mormon Church). But the variation in the influence of place on outcomes for individuals (in many cases differently by gender) and for household formation is important more generally. Other things equal, the places that produce the highest rates of households in which individual incomes are shared will tend to produce higher levels of household income than individual income.

. . . .Household formation, then, is an important and often neglected part of the story in the differences between places in terms of intergenerational mobility. (So too are the differences by gender, and we will be returning to that question in a future paper). While both individual and household income are of course important, including as measures of upward mobility, our view is that household income provides a better proxy for overall wellbeing.

. . . .Growing differences in marriage rates by parental background or between places may, then, be a bigger part of the mobility story than we previously thought. The research discussed here uses marriage as a convenient proxy for household income sharing, pointing to the fact that how income is shared is important for upward mobility and inequality. Thus, promoting household formation and stability is a policy priority.