That's the term the Census Bureau uses to describe the net number of people leaving or moving into a state or county; the other components of population increase/decrease are natural increase (the number of births minus the number of deaths) and international migration. The net internal migration in the entire country is, by definition, zero. I took a look the other day at the internal migration in counties and found that internal immigration and outmigration in the period 2000-05 is staggering. In 24 counties, there was a net immigration of more than 50,000. In 33 counties, there was a net outmigration of more than 50,000.
Here are the counties with net immigration of more than 50,000; for those whose knowledge of counties is unaccountably limited, I've added the names of the county seat or major city and the major metropolitan area of which it is a part:
|Riverside, Calif.||Riverside||Los Angeles||292,038|
|Clark, Nev.||Las Vegas||Las Vegas||219,112|
|San Bernardino, Calif.||San Bernardino||Los Angeles||120,496|
|Lee, Fla.||Fort Myers||93,478|
|Palm Beach, Fla.||West Palm Beach||West Palm Beach||90,812|
|Pasco, Fla.||New Port Richey||Tampa||88,650|
|Williamson, Tex.||Round Rock||Austin||61,219|
|Douglas, Colo.||Castle Rock||Denver||54,598|
|San Joaquin, Calif.||Stockton||54,651|
Note that most of these counties are exurban in character, at the edge of large metropolitan areas. The exceptions tend to prove the rule: Most of Maricopa Ariz., Clark Nev., Palm Beach Fla., Hillsborough Fla., Wake N.C., Sacramento , and Orange Fla. are exurban in character. The internal migration flow out from the central-city counties to exurban counties is immense.
Politically, 21 of these 24 counties voted for George W. Bush in 2004. The exceptions were two historically Democratic countiesClark Nev. (where Bush lost 52 to 47 percent) and Sacramento (where Bush lost by only 1,118 votes)and Orange Fla. (where he lost by 812 votes). The Bush percentages ranged up to 78 percent in Montgomery Texas.
Which counties had the biggest net internal outmigration? You won't be surprised to learn that most are big central-city counties; the five counties that make up New York City had a net internal outmigration of 808,562. Here are the leaders:
|Los Angeles, Calif.||Los Angeles||Los Angeles||562,351|
|Kings, N.Y.||Brooklyn||New York||291,748|
|Queens, N.Y.||Queens||New York||283,573|
|Santa Clara, Calif.||San Jose||San Francisco||201,499|
|Orange, Calif.||Santa Ana||Los Angeles||141,363|
|Alameda, Calif.||Oakland||San Francisco||132,607|
|Bronx, N.Y.||Bronx||New York||119,310|
|New York, N.Y.||Manhattan||Austin||112,677|
|San Diego, Calif.||San Diego||San Diego||97,536|
|San Francisco, Calif.||San Francisco||San Francisco||91,409|
|Hudson, N.J.||Jersey City||New York||76,172|
|San Mateo Calif.||San Mateo||San Francisco||72,802|
|Essex, N.J.||Newark||New York||61,223|
|Baltimore City, Md.||Baltimore||Baltimore||55,893|
|Nassau, N.Y.||Hempstead||New York||51,544|
What surprised me about this list is how many Sun Belt counties made it and how high up they ranked. Santa Clara Calif. and Orange Calif. were some of the nation's fastest growing counties from 1950 to 1990; now they have significant outmigration. In contrast, the internal outmigration from old industrial counties was less high up on the list than I would have guessed. What seems to be happening is that high immigration is pushing nonimmigrant residents out in greater numbers than industrial decline.
By the way, so much for Richard Florida's theory that "creative cities" are growth magnets. As you can see from the above, net internal migration is out of rather than into such creative cities as Manhattan, San Francisco, Seattle, and Denver.
Politically, 31 of these 33 counties (and county equivalents) voted for John Kerry in 2004, with the exceptions of still Republican-leaning Orange Calif. (60 to 39 percent for Bush, and he seems to have carried the Hispanic vote there) and historically Republican Hamilton Ohio (53 to 47 percent for George W. Bush).
Now let's look at metropolitan areas as a whole. The Census figures here are in most cases for the larger definitions of metro areas, but they keep treating San Francisco and San Jose, and Los Angeles and Riverside as separate areas. I've lumped them together in the rankings. Here the balance is toward net internal migration, with 18 metro areas having net internal immigration of more than 50,000 and only eight metro areas having net internal outmigration of similar magnitude.
Start with immigration:
|Las Vegas, Nev.||219,112|
|Dallas-Fort Worth, Tex.||100,167|
|Fort Myers, Fla.||93,478|
|San Antonio, Tex.||66,334|
|Fort Pierce, Fla.||59,489|
Note that just five metro areas have a net immigration approximating 200,000 or more: Phoenix, Las Vegas, Tampa, Atlanta, and Orlando. These are America's real boom towns these days. Note the small Florida metro areas that make the listFort Myers, Sarasota, Fort Pierce, Melbourne. I think it's a mistake to regard this immigration as entirely a matter of retirees. The Florida economy is booming, unemployment is very low and I think some of this represents private sector growth nurtured by the man I regard as the nation's best governor over the past dozen years, Jeb Bush. The Florida metro areas on this list have a total net immigration of 751,746; the Texas metro areas are second, with 304,258, just ahead of Maricopa Ariz.
Who are the net outmigration losers? It's a pretty concentrated list:
|New York, N.Y.-N.J.-Pa.||1,151,338|
|San Francisco, Calif.||506,241|
|Los Angeles, Calif.||291,180|
|San Diego, Calif.||97,536|
The nation's four largest metro areas are at the top of the list, though not in order of population. The tech bust of 2000 obviously accounts for much of metro San Francisco's outmigration, but this is probably not the whole story. These are metro areas with high immigration and high housing prices, and they're both combining to squeeze previous residents out. Those same factors are operating in Boston and San Diego. Only one old industrial metro area has substantial outmigration, my home metro area of Detroit; Philadelphia barely makes the list, with outmigration orders of magnitude less.
As I wrote this, I thought it would be useful to add the international migration figures to the table as well. So here goes:
|New York, N.Y.-N.J.-Pa.||1,151,338||865,533|
|San Francisco, Calif.||506,241||327,724|
|Los Angeles, Calif.||291,180||726,174|
|San Diego, Calif.||97,536||91,725|
Only Los Angeles and, at much lower levels, Philadelphia have more international migration than net internal outmigration; San Diego comes very close.
Let's see how the net internal immigration metro areas do on this score:
|Las Vegas, Nev.||219,112||52,899|
|Dallas-Fort Worth, Tex.||100,167||232,235|
|Fort Myers, Fla.||93,478||10,075|
|San Antonio, Tex.||66,334||27,063|
|Fort Pierce, Fla.||59,489||5,065|
Only in the two large Texas metro areas, Dallas and Houston, does international migration exceed net internal migration. There's much less international migration in Austin and San Antonio, though they're closer to the Texas border.