Forbes posted an interactive map last week showing domestic migration patterns into and out of American cities. Here's what it looks like for New York:
Compared to San Francisco (which has mostly inward migration) or Detroit (mostly outward), New York appears to show a relatively balanced mix of people moving into and out of the city. But have a look at this chart, taken from a report by the New York Department of City Planning:
As you can see, from 2000-2007 New York lost quite a few more people to other states than it gained from them. The city's population continued growing for a couple of reasons: First, the net domestic out-migration was partially offset by immigrants from other countries. Second, the number of births in the city outnumbered deaths by more than the number of people lost from net migration.
And it's been like this since the end of the 1970s:
I always get a surprised reaction when I tell someone that more people leave New York each year than arrive. The common understanding seems to be that New York is such an attractive place that for every person that leaves, someone will always be willing to take her place.
But that's not really how it works. Sure, people love coming here, but a lot of people also get tired of being here after a while. Some go back to their home state. Some will stick around long enough to start a family before moving to a more child-friendly place. And some who emigrated here from abroad because of the city's ethnic neighborhoods, or because they had family here, will find reasons to try somewhere else.
The city maintains its vitality because the people who come here to take their places tend to be "concentrated in the young working ages, which has been relatively unchanged since 1980. More than two-thirds of all in-migrants to New York City were between 18 and 44 years of age, with almost one-half between 25 and 44. This reflects the important impetus that New York City’s labor market opportunities provide for both new immigrants and native-born young people from other parts of the nation."
The report concludes that young people and immigrants "continue to energize New York, fueling the city’s labor force, creating and frequenting its businesses, and sustaining its neighborhoods."
It's no secret that New York is one of the most tolerant American cities for immigrants. This is partly attributable to historical reasons, but it's also because immigrants do their part to keep the population stable and growing. Owing to their higher fertility rate, they account for a healthy portion of the "natural" growth shown above. They make it possible for the city to have the kind of "churn" described in the paper.
I can't find more updated numbers, but to back this up a bit, as of 2000 about 50% of all births in the City were to foreign-born women; adding together immigrants and their offspring born here accounts for 55% percent of the people in New York. (That's from page 35 of this report (pdf), and see also page 4 of this one (pdf) to read more about how this impacts specific neighborhoods.)
And most anybody who has lived here long enough will recognize the importance of immigrants to the labor force. Too many more numbers will bore you, so instead I'll just post another pretty chart (click for full size):
So if you wonder why New York residents are more favorably disposed towards liberalized immigration policies, it's not just because we're so far from the country's southern border or because we're all a bunch of squishy East Coast liberal types. The benefits of being surrounded by a large immigrant presence are tangible here.
A couple of paragraphs from the report about the destinations of New York's out-migrants, plus another chart, are beneath the fold:
As difficult as the economic picture is, we are likely to see more people stay put, because of the lack of alternatives in traditional destination areas for New York out-migrants. It may even be the case that more people will seek out New York as a good place to endure the brunt of this recession, given the diversity of its economic opportunities. Just like with the demise of manufacturing in the mid-20th century, it is likely that the energy that is embedded in New York’s population will, once again, be the impetus for the next wave of change in economic conditions. ...
...the destination patterns of out-migrants have been remarkably similar over the past 30 years. The largest contingent heads for the Middle-Atlantic states, to the New Y ork-New Jersey Metropolitan Region, between 40 and 50 percent of the total outflow. Two changes have occurred over the period: The propensity to head to the South Atlantic states has increased, especially among black out- migrants to states where their migration originated and among Hispanics, especially Puerto Ricans, to Florida.