Different Data Sources Tell Different Stories About Declining Geographic Mobility

by George Masnick
Fellow

The Census Bureau recently released its usual extensive Current Population Survey (CPS)-based package of tables on geographic mobility for 2011-12.  A new feature of this release is a series of historical charts, one of which is reproduced below. Examining just the last decade, mobility rates took a sharp turn downward in 2007-08, with most of the decline occurring in moves between states (Figure 1).  This sharp decline has been the impetus for many stories about the decline in the geographic mobility rate and its implications for housing (see this example).  Most have assumed that the mobility decline was caused by the Great Recession: with reduced job opportunities across the country, there was less inducement to change residence in search of employment, particularly among young adults who were unable to leave the parental nest. Some have asserted that the loss in housing values and tight mortgage lending have “locked in” owners who otherwise would like to move, especially those owners who are now under water on their mortgages.

Figure 1

Source: U.S. Census Bureau, Current Population Survey, 1948-2012, select years.

Yet some recent efforts to scrutinize mobility rate trends and associations have raised doubts about the basic facts. Research at the Minneapolis Fed suggests Interstate Migration Has Fallen Less Than You Think.  Another series of papers have debated the strength of the association between negative equity and reduced mobility. Findings published in 2010 that owners with negative equity are one-third less mobile were challenged as largely a result of the authors dropping some negative-equity homeowners' moves from the data.   The challenge received a rebuttal that was lukewarm at best.

But a more fundamental question is whether there was indeed as sharp a decline in mobility in the late 2000s as the CPS data in Figure 1 suggests. Since 2006 the Census Bureau’s American Community Survey (ACS) has also provided annual estimates of mobility rates that are consistently higher than those of the CPS and suggest a different trend (Figure 2). One factor contributing to higher ACS rates could be that, starting in 2006, the ACS included in its sample the more mobile institutional population. In contrast, the CPS sample excludes most people that live in group settings such as correctional facilities, military barracks, and college dormitories.  The Census Bureau has recalculated the ACS mobility rate based only on the population living in households for 2006 through 2009.  These modified ACS rates plotted in Figure 2 are significantly lower than those with the group quarters population included, are in line with the long-term more gradual decline in the pre-2000 CPS trend, and definitely do not show as sharp a decline around 2007.

Figure 2

Source: Current Population Survey (CPS) and American Community Survey (ACS) published tables.  The Census Bureau has recalculated the ACS mobility rate based on population living in households for 2006 through 2009 (www.census.gov/prod/2011pubs/p20-565.pdf).  The ACS did not cover the entire U.S. until 2005.

The differences between the ACS and CPS mobility rates in Figure 2 are supported by additional analyses of inter-county and inter-state migration trends from these two sources. This research also shows that the ACS levels and trends are mirrored almost exactly by migration rates from IRS data, further adding credence to the ACS. Mobility rates of household heads calculated from the American Housing Survey (AHS) also closely follow the levels from both the ACS and the IRS data.  The persistently lower rates of mobility in the CPS since 2000 are not well understood, but might be explained by the CPS data being collected primarily by a telephone survey that might not fully reflect the recent growth of cell phone-only households - assuming that those households contain persons that are among the most mobile.  (The ACS is primarily a mail survey, IRS data are from filed tax returns, and the AHS follows the occupants of particular housing units over time.)

If there is a story in the ACS trend, aside from one of gradual decline over the long-term, it is that the period immediately leading up to the Great Recession was one of above-trend mobility.  More people were moving than might have been expected during the peak of the housing boom. IRS migration trends in the analysis cited above support this story as well.  The bursting of the housing bubble has mostly just returned geographic mobility rates to their long-term trend.  The long-term decline in mobility is likely due to a host of broad social, economic, and demographic trends: the aging of the population; delays in the transition to adulthood; the increase in dual-career households; the changing race/Hispanic origin of the population; more working from home; more homogenized employment opportunities across different locations; the increase in long-distance commuting patterns; etc.  Absent another housing boom, we should expect near-term mobility rates to continue to gradually decline.