Interesting fact of the day

Here is an interesting fact, courtesy of this paper by Ed Glaeser and Charles Redlick:  Although we typically assume that metropolitan areas like Detroit are shrinking because their residents are fleeing for better opportunities, this isn't true.  Fast-growing cities also have high rates of out-migration.  In fact, the faster a city grows, the more likely are its residents to move away during a given year.  Cities decline because they attract fewer newcomers, not because their residents are more likely to move elsewhere.   

Austin, interestingly enough, proves the rule.  Although the Austin-San Marcos MSA enjoyed phenomenal growth during the 1990s, Austin residents were much more likely to emigrate during that period than the residents of almost every other city they examined.  (The exceptions were San Francisco and Charlotte, whose residents were still slightly less likely to emigrate.)  

(And, no, it is unlikely that the mere presence of UT accounts for Austin's high rate of emigration -- the Census Bureau does not count a student as a city resident unless he maintains his permanent residence in that city.)

Austin's high rate of out-migration and even higher rate of in-migration means that its population churns unusually quickly; i.e., newcomers make up an unusually large percentage of its population.  This likely explains some of the friction between the old guard and the new guard (or "Californians," as they are more derisively known). Old-timers are shrinking as a percentage of Austin's population faster than anywhere else.