My colleague Robert Samuelson recently wrote about the fact that Americans are moving around the country less frequently than they used to. This decline in geographic mobility has puzzled economists and demographers, and there are multiple theories behind it. Possible explanations include the general decline in job opportunities around the country (which Samuelson focused on); the aging population; underwater mortgages, which make it harder for people to pick up and move across the country (so-called “housing lock”); telecommuting; regions becoming less specialized in what kinds of goods and services they produce, giving people less reason to move if they want to change careers; etc.

I have another pet theory that I haven’t seen much written about: child-care lock, driven by women’s higher labor force participation rates.

Prime-working-age women are more likely to be in the labor force today than they were several decades ago. There are two ways this could discourage mobility. One is that in a two-earner family, co-location is difficult. Maybe Dad got offered a promotion a few states away, but if he wants to take it, Mom now has to find a new job, too.

That’s a way that women’s greater likelihood of working might discourage couples from moving. Even for singles, though, women’s higher labor force participation may make it hard to relocate, at least if there are kids involved. Why? Because parents, especially single parents, frequently rely on relatives and local social networks for child care.

Day care is really friggin’ expensive, costing more than public college tuition in most states, and its cost has been rising over time.

day care costs

Both because of these costs and presumably personal preferences, about a quarter of kids younger than 5 regularly receive child care from their grandparents, according to the Census Bureau. The share is higher (more than 30 percent) when Mom is employed.

Among the young children of working moms, the share whose primary care arrangement involves grandparents has generally been rising over time.

Source: Tabulations derived from Current Population Reports.
Source: Tabulations derived from Current Population Reports

In other words, maybe workers are reluctant to relocate because they would lose their trusted care networks. This might become an even bigger issue going forward if the share of kids living in single-parent families continues to rise.

I’ve spoken to individual workers for whom this has been true (e.g., single moms who were reluctant to move because they needed family members to watch their kids during working hours) but have not yet been able to find any good data showing how child care arrangements affect mobility at a more macro level. If you know of any good research looking into child-care lock, feel free to shoot me an e-mail.

Catherine Rampell is an opinion columnist at The Washington Post.