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Warm Januaries and Cold Julys: Climate Doesn't Affect Human Migration Patterns

When it comes to migration, it's all about economics and proximity.
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Pittsburgh in winter. (Photo: Navin75/Flickr)

Pittsburgh in winter. (Photo: Navin75/Flickr)

Are you familiar with Randy Pausch's Last Lecture? I met Professor Pausch before he died of of pancreatic cancer. It was a brief encounter in a doorway at Carnegie Mellon University in Pittsburgh. I had no idea who he was when I met him. Our exchange haunts me to this day. I was introduced as the guy who will bring back the people who left Pittsburgh. In response, he explained to me that one of his great regrets in life was enduring a Pittsburgh winter. Ouch, I felt like I was on a fool's errand.

As a veteran of winters in Minnesota, Vermont, and Upstate New York (near Schenectady), January doesn't bother me. It's easier in Colorado than in Michigan. I won't pick one place over another in order to bask in ironic sunshine. I don't wake up in the morning thinking about my epitaph, either. A conversation between bloggers:

Aaron Renn, aka the Urbanophile, asked an interesting question on Twitter today as we look down the barrel of another heavy snow: “how does this winter affect perceptions of the city’s desirability to live in?”

As a Southerner, I’d protest that we’re at a disadvantage because it’s hard to headline the grinding oppressiveness of the summer down there—you can put on as much clothes as you want, but you’re legally limited on how much you can take off. And when Chicago gets as hot as it is in Baton Rouge, you’ll be mad you moved to Houston. Or your grandkids will, at least, as they pack their bags for sunny, mild Edmonton.

Still, point taken. Renn pointed me towards the work of Edward Glaeser, the Harvard economist and U. of C. grad who’s become one of the most prominent analysts of the American city in the 21st century. And he thinks there’s a strong correlation. He’s got a whole paper on it, in fact: “Smart Growth: Education, Skilled Workers, & the Future of Cold Weather Cities.”

Winter in the Rust Belt is usually an endurance test. Why suffer in Peoria when you could labor in Mobile? Fancy regression graphs and all, migration doesn't mind amenities such as climate. January temperatures be damned. There's shale oil to be found in North Dakota. The rush is on. Ever hear of Flin Flon?

To honor Glaeser's analysis, I can't pick out a few exceptions to prove the rule. That's not fair. But a natural experiment is fair. We can compare and contrast miserable January places with other miserable January places. Or, muse about lovely January climates in concert with other lovely January climates. Apples to apples. Also, we can consider covariance. The South, with its warmer January, should economically converge with the wealthier North. Just so happens that the balmier state was stuck in economic retrograde during the 19th century. Mississippi "catching up" is inevitable.

When I was studying for comprehensive exams on the topic of migration (in the field of geography) I don't remember much about climate. I have a scientific background in meteorology. A warm weather wander would stick out to me. Mostly, to answer exam questions, I had to master rational choice. Eighty percent of migration is economic. For the rest, the error in this lovely model, proximity eats it. Burp.

Concerning migration, proximity is a big deal. People are risk averse. Moving a long way for a humid embrace scares away most. That's a nice story, but Glaeser's nifty economic geography (retirees moving en masse to Florida or Arizona) still stands. Well, not really.

Glaeser runs mean January temperature against population change. Earth to Harvard, big migration from a warmer January in Mexico to nearby United States is not a revelation. How much of the population growth for Sun Belt states comes in the form of migration from as warm (or warmer) places? How much of the population gains come from higher birth rates of Hispanic migrants?

Why are Mexicans moving to Chicago? "The Chicago region is home to more than 1.5 million residents of Mexican descent and Chicago has the second largest Mexican population of any city in the United States behind Los Angeles." Mexicans can move to the Sun Belt, too. They choose Chicago. So much for climate.