What Happened to Migration in 2016?
A First Look from the Current Population Survey
Last week, I wrote about the American Community Survey’s migration data. But we also recently got data from the Current Population Survey. I did not cover it because Census won’t be releasing the detailed migration data for some time yet, and because, as I rule of thumb, I don’t do microdata unless I really have to. But the ever-helpful Jed Jolko, who wrote specifically about labor-force migration in the new CPS data, was kind enough to pass along the headline gross migration rates, as he is a microdata fetishist, and so downloaded all the microdata before even IPUMS has it all. If that sentence made no sense to you, that’s fine, just move along to the brightly colored graph below.
The key lines for this post are the blue ones. It’s a weird trend. Usually, intercounty (so moving across state lines within the same state) and interstate migration more-or-less move together. But for 2016, they did not. Intercounty migration rose substantially, while interstate migration gave up its gains from 2015. That’s odd.
I have no detailed demographic data, and won’t until Census releases their detailed migration tables. But, in the meantime, I want to hit a totally different topic: the timing of migration data!
The ever-insightful Gray Kimrough got a bit peeved recently about the mis-use of ACS income data, so produced this fun visualization comparing the time periods relevant to CPS vs. ACS estimates of income:
Such charts inspire me, as anyone who’s read my user-guide to IRS migration data knows.
But sadly, Gray’s chart does not reflect how CPS asks about migration. For migration, CPS asks this set of questions:
In other words, the CPS ASEC is asking, in March 2016, where you lived in March 2015, and differences indicate migration. So it’s not quite the same as CPS income data.
Anyways, the chart below gives a guide to when the “migrations” reported in each source actually occurred:
CPS is straightforward. Moves from March 1 to March 1 get captured. Easy-peasy. IRS gets more complicated. I won’t repeat here the elaborate explanation I’ve given before, but you can get all the details on the very unusual reporting window for IRS migration data in my user-guide to IRS data. TL;DR version: IRS data has no standardized reporting window for migration.
Finally, we get to ACS. ACS migration data comes from monthly surveys that are averaged and weighted across the year. These surveys ask about the prior twelve months. So surveys in January of 2015 will overwhelmingly be about 2014 migration. In other words, the ACS has a very wide sample window, with prior-year-December up to current-year-February being the most densely-covered months.
Because migration is seasonal, these different coverage windows can matter. The upshot of all this is that the CPS data from March 2016 surveys is likely to more closely match ACS-2016 data than ACS-2015 data. As such, we should see this ambiguous CPS migration data as a first look at what other data sources are going to tell us about migration in 2016.
Check out my Podcast about the history of American migration.
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I’m a graduate of the George Washington University’s Elliott School with an MA in International Trade and Investment Policy, and an economist at USDA’s Foreign Agricultural Service. I like to learn about migration, the cotton industry, airplanes, trade policy, space, Africa, and faith. I’m married to a kickass Kentucky woman named Ruth.
My posts are not endorsed by and do not in any way represent the opinions of the United States government or any branch, department, agency, or division of it. My writing represents exclusively my own opinions. I did not receive any financial support or remuneration from any party for this research. More’s the pity.
