When the Sun Stops Shining
New Mexico’s Dismal Demographic Experience
We often hear that Sunbelt states are growing because of all sorts of legendary benefits: a favorable climate! Federal industrial preference during the Cold War! Low taxes and weak unions! Some of these have more merit than others.
Perhaps the worst of all explanations for population shift southwards is climate. Today, I won’t go in depth on why I dislike climate as an explanation for modern migration patterns, but we will look at a fun case study: New Mexico.
While new Mexico’s population growth usually surpassed the nationwide average for most of its history since territorial organization in 1850, in recent years it has plummeted below average. Indeed, in 2014 and 2015, the U.S. Census Bureau thinks that total population growth was negative: the state’s population actually fell.
Of course, this has happened before. Two wartime mobilizations clearly show up in the data, as does a dip in the late 1960s, the exact origin of which I’m unclear about. It could be a commodity boom cycle. It could be the end of the Bracero Program in 1964. It could be changed Federal employment way back then. I don’t have exact data, but Walker Air Force Base did close in 1967, and apparently had 5,000 employees. That seems like a very plausible candidate. Statewide employment data doesn’t give any indication of a generalized recession or economic weakness.
The late 1960s don’t look bad to me. The early 1960s do show maybe some economic weakness, but not the later period.
Anyways, I’m not 100% sure what caused this past population drop. But that’s not my main area of interest. My main area of interest is in more recent trends.
What happens if we compare New Mexico to some peer states, say, its border states of Arizona, Texas, Oklahoma, Colorado, and Utah?
Notice that, from 1950 to about 1995, New Mexico’s growth roughly approximated growth rates in its peer states. Then it suffered in the late 1990s, recovered some in the 2000s, and has since been really struggling again. Lest you should think that this is just Texas dragging the numbers up, I’ve also included the “border states” exclusive of Texas. The only border state to have similarly poor performance as New Mexico is Oklahoma, and its border with Oklahoma is extremely short, with its population centers located quite far away.
So you should be convinced by now that New Mexico is experiencing remarkable population weakness, and that that weakness is extremely atypical for its region.
Can Climate Explain This Population Change?
Do we have any reason to believe that Mexico’s population growth went from over double the national growth rate in 1995 to negative rates in 2014–2015 because of changes related to climate?
Before this sounds insane, let me clarify a few things. First, we have documented, measurable long-run trends in regional climates. If weather impacts migration, then we might expect changed migration patterns to be associated with changed weather patterns. I’ll give you a spoiler: there’s virtually no association between changed local-area average temperature and changed population growth or migration rates.
“But of course” our climate apologist cries out, “That’s because of air conditioning.”
…
Okay, so air conditioning may have altered the habitability of some areas as it was being adopted. By 1953, over a million AC units were selling per year in the US. By 1973, over half of American homes had AC. Today, it’s 90% or so. AC adoption was faster in the south than in the north. So AC probably did enable movement south… but wait a second.
Did millions of people move south because they’d been dying to move there for years and years and years but it was too hot, and now they could finally keep cool? Really?
No: jobs moved! The military industrial complex, less unionized workplaces, Federal investments, major university system expansions, improved infrastructure, civil rights laws, and diasporan return with skills acquired in the north all created major new opportunities. Without AC, this growth would have been slower, but the idea that the American economy was waiting on air conditioning to unlock the economic potential of the south is bonkers.
And by the 1970s, air conditioning was so universally available in the south that it’s hard to say anything post-1970s is driven by AC. The reality is that climate control also improved in cold places, so that Americans everywhere live in greater climatic comfort than ever before.
But wait, there’s more!
Since the 1970s, we’ve seen similar-climate states evince huge variation in growth rates. And a large part of population growth in Sunbelt states has been driven by immigrants moving from places often hotter than the American Sunbelt. And another large part of population growth hasn’t been associated with migration at all, but is driven by the Sunbelt’s lower death rate and higher birth rate, because the Sunbelt is younger and more minority-dense.
Finally…this whole bit about climate… are we sure hot weather would be attractive? Do a straw poll of your friends. Ask them if they prefer hot, humid summers or cold, snowy winters. Even many of my southern friends tend to say they’d rather deal with cold winters than swampy summers. The reality is that the share of migration to the Sunbelt that’s actually people looking for climate amenities is almost certainly quite small, and there’s probably also a nonzero population moving away from the Sunbelt due to climate disamenities. Core economic factors matter more.
The point is, climate preferences are not as simple as “hot and sunny is good.” Climate preferences exhibit substantial heterogeneity, and may vary across time as well. So the question is: could New Mexicans have suddenly soured on New Mexico’s actual climate? Forbes does score NM poorly for “quality of life” in their indices, but I can’t tell if this relates to climate. Gallup found New Mexicans in 2014 much less likely to identify their state as the best place to live than most Americans, but, again, not sure if that’s because of weather. This news article says New Mexico has among the least natural disasters of any state, which seems like a climate plus to me. FEMA shows no disasters since 2014. This paper says New Mexico’s average temperature has risen 2.7 degrees in 45 years, so, if warmer makes a state better, and if there have been no accompanying disasters, this should boost migration, right?
Anyways. If you have evidence of a binge of local-weather-hating by New Mexicans, I’d love to see it. Barring such evidence, though, I’m going to return to the default assumption that climate has basically no direct effect on migration.
New Mexico’s Migration Record
Let’s start with a really far-back reach for migration. Data before 1990 is not as good as since then, but some data does exist. In fact, I can get multiple sources of direct or imputed migration data back to 1900. So that’s how far back we’ll go to look at New Mexico’s migration record.
There are lots of lines there from lots of sources. For simplicity, I have taken a simple average of all my available sources to develop an estimated annual net migration rate. This is a little bit haphazard and there are certainly errors, but while some of the details may be wrong, the general trends should be pretty accurate.
As you can see, New Mexico’s net migration rates have turned negative in recent years, just as they did around the late 1990s when growth slowed down, and just as they did in the late 1960s when growth turned negative. In fact, we can decompose New Mexico’s growth rate as “domestic net migration” and “other,” which includes both natural increase and international migration.
As you can see, New Mexico’s “other growth” had been equal to or above its net migration rate essentially from 1900 to the mid 1980s. However, New Mexican net migration seems to have begun a long slide into more negative net migration around the 1970s. Each peak in net migration has been lower, each trough deeper.
At least since 1990, we can also decompose the “other” category into international migration and natural increase. So let’s do that. For this, since I’m using an all-recent-years window of time, I’ll abandon my multi-source estimate and go with the Census Population Estimates time series.
There are several things to notice here. First, falling net migration has been associated with falling natural growth as well. Media reports have suggested that outflows have largely been young people, while inflows are Snowbirds, which could accelerate the decline in natural rate of growth. I’ll test these claim below. But for now, notice that international migration is also a bit lower. New Mexico has no demographic source of strength in any of the major pillars of demographic change.
But, hold on, is that decline in natural increase actually that odd? Let’s compare to the nation on the whole.
Well there’s yer problem.
Since 1990, New Mexico’s rate of natural increase has fallen at a far faster rate than the nation on the whole. This convergence has come about equally from both birth rates and rising death rates. New Mexico used to have higher birth rates and lower death rates than the nation on the whole, and now has essentially equivalent birth and death rates. The amount of convergence has been roughly equivalent. Regardless of New Mexico’s net migration rates, if natural population growth continues to plummet, population will stagnate or fall.
New Mexico’s dilemma is very similar to West Virginia or Maine in this regard. This is remarkable, because New Mexico is not what we think of as a kind of “aging” or “fading” or “decaying” area.
But you see, it turns out that attracting retirees isn’t a really great population growth strategy! Old people have higher death rates, and are unlikely to produce children. They’re a drag on population growth. And if a large share of people are a drag on population growth, then they’re a drag on a host of other economic outcomes.
Is New Mexican Migration Age-Biased?
So, let’s check the data. Is migration into and out of New Mexico age-biased? For this, we’ll use ACS data. The aggregate numbers won’t quite match PEP as shown above, but the broad story should be similar.
The yearly ACS data is extremely noisy. So, to spare you some of that, I’ve shown cumulative migration.
Let’s go from youngest to oldest. The pale blue line represents migrants under 18 years old. Until 2006, New Mexico was gaining minors; but it has been losing them most years since then, and has now forefeited essentially all the gains it made from 2001–2006.
New Mexico lost 18–30-year-olds until about 2005, but since then has actually seen its record improve. Rationally, we might expect these migrants to be potential parents. They should be boosting crude fertility rates in New Mexico!
For 31–55-year-olds, we see the strongest net migration record, which New Mexico having gained them until 2012. Since 2012, these prime-age earners have begun to leave the state. Finally, for retirees and near-retirees (ages 55+), net migration was positive until 2011, and has declined some since.
So, there may be some demographic replacement, especially recently. For a while, young-parent-age people were exiting. Kids have been departing for a while. Older groups have shown much more robust migration. But more recently, we’ve seen the young-parent generation return to New Mexico… even as the older-parent generation starts to exit, and retiree inflows start to reverse themselves.
New Mexico’s enduring demographic problems may stem from migration-driven generational replacement, but its recent problems arise from worsening migration for all groups except Millennials, as well as worsening natural population growth.
If Not Generational Replacement, Then What?
So if generational replacement isn’t the whole story, then what is it?
Well, we can look at fertility rates for women.
Most births occur among women who are in the 20–25 or 26–35 range. For New Mexico in this sample, those two age groups ranged from 70% to 85% of all births. At the start of the sample, teen pregnancy and 36+ pregnancy were about the same share of all births, about 13%. By 2015, however, teen pregnancy had fallen to about 6% of all births, while 36+ ranged from stable at about 12%, to potentially as high as 18% of all births.
But what we should note is that while fertility rose for older moms, it declined for teen moms and it declined for early moms (20–25). For women ages 26–35, fertility was about steady.
We can also compare New Mexico’s fertility to national fertility rates.
As you can see, New Mexico does have higher fertility than the nation on the whole. Its fertility rates have declined at about the same rate as the rest of the country. So this declining fertility rate isn’t an exclusively New Mexican problem, it’s just one exacerbated by a moderate amount of generational replacement through migration, slightly slower international migration, and negative domestic migration. It’s also possible death rates have worsened.
Conclusion
New Mexico’s experience is a harbinger. Their net migration rates are not, in historic terms, particularly severe, and their fertility rates are higher than the US average. But as fertility declines and populations age, local population growth becomes even more sensitive to migration. Eventually, the day will come when migration is virtually the only source of population growth, unless we all do our moral duty to the future and produce a hearty supply of strapping young children. In New Mexico, we can see a foretaste of the demographic future of many Sunbelt states: and so other states would do well to watch and learn.
Check out my Podcast about the history of American migration.
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I’m a native of Wilmore, Kentucky, a graduate of Transylvania University, and also the George Washington University’s Elliott School. My real job is as an economist at USDA’s Foreign Agricultural Service, where I analyze and forecast cotton market conditions. 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.
