Where America Is Moving (hint: it's not New York).

The U.S. Census Bureau's population estimates for 2015 are out this morning. The headline findings are that North Carolina's population passed 10 million and Florida added more people than California for the first year in almost a decade.

The numbers, arriving at the halfway mark between decennial censuses, also provide a chance to assess the direction of U.S. growth, economic and otherwise, during this recovery. The total U.S. population was estimated at 321.4 million as of July 1, up 12.7 million, or 4.1 percent, from the last census in April 2010. Seventy percent of that growth occurred in these 10 states:

The fastest growing states in percentage terms were North Dakota, the District of Columbia (which isn't exactly a state) and Texas, but the D.C. and North Dakota gains were in the tens of thousands and thus have no real impact on the national picture. Which states weren't growing?

Puerto Rico isn't part of the overall U.S. totals cited above, but I couldn't resist including it here because the numbers are so dramatic. The territory, which has been stuck in an outright economic depression for a while now, lost 6.8 percent of its population in just five years.

The states that added the most people from 2010 to 2015 tend to be big and on a coast. In terms of regions, the biggest gainers in both numbers and percentage were the South (which in the Census Bureau's accounting stretches from Texas to Delaware) and the West. It's interesting that New York made the top 10 list, though. Does this mean Americans are flocking to the Big Apple again?

In a word, no. The Census Bureau also tracks net domestic migration. Here are the 10 states that added the most people from elsewhere in the U.S. since 2010:

And here are the 10 states with the biggest losses to domestic migration:

So New York has been hemorrhaging residents to other states. The only reason its population has nonetheless grown is that:

• New Yorkers have been having lots of babies, with 1.3 million births to 792,242 deaths.
• Lots of people (630,763 since 2010) have been moving to New York from other countries.

The same holds for the other states on the domestic out-migration top 10 list -- births and overseas immigration prevented outright population loss. The only states with more deaths than births were West Virginia and Maine; the states with the least net immigration from overseas (fewer than 5,000 people each) were Wyoming, Montana and Vermont.

What is one to make of these population shifts? I see three main causes:

1. Aging baby boomers -- the generation's leading edge will begin turning 70 next month -- are moving to where it's warmer.
2. People are moving away from economically depressed places (Puerto Rico, West Virginia) to where there's more opportunity (Texas, Colorado).
3. People are moving from places where real estate is expensive to where it's cheaper.

This last phenomenon is one of the most intriguing and troubling of our time. Californians are moving to Arizona, Oregon and Washington. New Yorkers are moving to Florida, Georgia and North Carolina. Everybody is moving to Texas.

Yet this usually isn't a case of moving to opportunity, a healthy phenomenon that promotes economic growth. New York City and California's coastal metropolises are economic juggernauts, reaching new heights in productivity (economic output per hour worked) and creating lots of new high-wage jobs. Yet people are moving away from them. As the Economist's Ryan Avent put it in "The Gated City," an excellent (and short!) 2011 summary of this phenomenon, "millions of Americans are moving from high-productivity cities to low-productivity cities." They're doing this because they can't find affordable housing in those high-productivity cities or near enough to commute there.

The reasons for this are many. It's partly demand, partly geography, partly inadequate investment in transit, partly zoning and other land-use restrictions that make it hard to built new housing in high-cost cities. In a recent paper, Chang-Tai Hsieh of the University of Chicago and Enrico Moretti of the University of California, Berkeley estimated that Americans' tendency to move from high-productivity regions to low-productivity ones had reduced U.S. gross domestic product by 13.5 percent. They figured that regulatory constraints on housing alone depressed GDP by 9.5 percent.

There's also been a long decline in the percentage of U.S. residents who move each year. Overall, it appears, not nearly enough Americans are moving to opportunity.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

A link to the original post can be found here.