Saturday, March 28, 2015

Do Air Conditioners Explain the Rise of the South?

Paul Krugman says yes and yes:
The rise of the US sunbelt can be understood largely as a response to the emergence of widespread air conditioning, which made places that are warm in the winter attractive despite humid, muggy summers. It’s a gradual, long-drawn-out response, because location decisions have a lot of inertia[.]
And this:
[T]here’s a real demographic turning point for the South circa 1960, as a steadily falling share of the total US population shifts to a sustained rise...this turning point coincides with the coming of widespread home air conditioning. So when you ask why Sunbelt states have in general grown faster than those in the Northeasy, don’t credit Art Laffer; credit Willis Carrier.
This is an intuitive explanation, but it is incomplete and cannot explain recent net migration patterns within the United States. On the first point it is important to note that the South's economy actually began to accelerate in the 1930s and 1940s.


This takeoff is one of the great stories from 20th century U.S. economic history. From the close of the Civil War up through World War II, the South's economy had been relatively undeveloped and isolated from the rest of the country. This eighty-year period of economic backwardness in the South stood in stark contrast to the economic gains elsewhere in the country that made the United States the leading industrial power of the world by the early 20th century. Something radically changed, though, in the 1930s and 1940s that broke the South free from its poverty trap. From this period on, the South began modernizing and by 1980 it had converged with the rest of the U.S. economy. But why the sudden break in the 1930-1940 period? 

There have been a number of attempts to explain this sudden change in the trajectory of the South. Gavin Wright (1997) attributes it to the opening up of labor markets, Connolly (2004) looks to improved human capital formation, Cobb (1982) points to industrial policy, Beasley et al. (2005) finger increased political competition, Bleakley (2007) sees hookworm eradication as important,  Glaeser and Tobio (2008) look to housing regulations, and Bateman et al (2009) see the large public capital investments in the South during the 1930s and 1940s as facilitating a 'Big Push' for the region. The takeaway is that there were probably many factors that supported the rise of the South, not just air conditioning.

The other problem with looking to air conditioning as the reason for the rise of the South is that there are recent net migration patterns that show movement into the warm South from other warm regions. not just from cooler regions. For example, this Census Bureau figure shows for the 1995-2000 period net migration out of California often went into other warm states, including many in the South. 

To further illustrate this point, he next three figures focus in on three big counties in Texas: Harris Country (Houston), Dallas County (Dallas), and Travis Country (Austin). They all show for the years 2008-2012 net inflows coming from southern California where it is also warm (source): 

So air conditioning cannot be an important story over this time. It may have contributed, along with the other factors listed above, to the the initial takeoff of the American South, but not so in recent decades. The rise of the South is a far more complicated story.


  1. Both California and the South are warm states, however the difference that air conditioning makes in California versus a state like Texas is very different. Air conditioning has a much bigger impact in state like Texas, since the summers are so much hotter and more humid, despite both being warm states. Someone who might not have moved from California to the South without air conditioning would therefore be much more likely to make the move once there is air conditioning available, which to me seems to support the Krugman view, or at least isn't a point against it.

    1. So air conditioners are not important in places like San Diego and Los Angeles (where the map indicates much of the net migration into Texas comes from)?

    2. Having grown up in Southern California, I can tell you that you *can* live comfortably without air conditioning, particularly if you live close to the ocean. A ceiling fan, a roof vent, selectively closing and opening windows and well-situated trees will do the trick. Since the air is not humid, indoor air can stay cool for quite some time; as long as there are shade plants and some indoor fans you will do fine.

    3. If you have to live close to an ocean, selectively close and open windows, have strategically placed trees, a ceiling fan, roof vent, etc. that is a lot of work and doesn't sound all that different than living in Texas prior to AC. Maybe on the margin, CA is more tolerable but given your description both benefited from AC.

    4. It boggles my mind how ready people who have never tried living somewhere and really have no idea about the place in question are to explain to people who have lived there all about it.

  2. Air conditioning was one big factor. Summers in CA, where most people live near the coast, are much easier to endure than inland summers in the south. There's a reason the British ambassador to the US used to get a tropical pay supplement for having to live in DC, and DC is just barely in the south. You should also consider how much of that migration to the south was retirees moving to the gulf states. Retirees don't have to work, and they are often older people who prefer warmer weather.

    The other big factor, though, was the interstate highway system. Until fairly recently, railroad tariffs were totally biased in favor of northern manufacturing and southern raw materials production. There was no, what we would call nowadays, "network neutrality". A carload of iron ore cost less to send north than south, but a carload of iron bars would cost less to send north to south. Investment was controlled out of NYC and, to a lesser extent, Boston, and the railroad owners were also the owners of the big industrial firms. They redlined the south until the Federal government stepped in.

  3. in, iirc, galbraiths bio a life in these times
    so as the WWII effort ramped up, all the large contracts went to the expected industrial states like OH PA NY
    there was a desire to have some contracts in the south, but sidney hillman was adamant that no right to work state get a contract
    so i call up the congressman from Birmingham AL, a neanderthal, and say I have a contract that will generate 25,000 jobs, but you have to change the rtw law to allow unions
    so the congressman says, rtw laws are a bedrock principle to me, but for 25,000 jobs to hell wiht principles...

    or, simplistic analysis if role of gov't jobs not mentioned (do you know how to spell L-B-J ?)

    beyond that, the rise of the south from benighted rural menckian backwater to modern civilization..are you really saying AC didn't play a role ?
    that cold winters like the one we just had in the NE didn't play a role ?
    really ?

  4. re the "proof" in your last 3 graphs
    you really think the climate in CA is as hot and *humid* as in Houston ?

  5. That Krugman would dumb down something complex for the sake of schlock socia-economic commentary is, regrettably, entirely to be expected.

  6. The recent death of the first President of Singapore prompted reviews of his reasons for the success of the development of Singapore. One reason given was air conditioning.

  7. Yea, those dumb clucks down there could not have accomplished this on their own. Did he mention that A.C. was invented by a northerner?