Saturday, March 31, 2012

Gross Migration Versus Net Migration

Aaron Renn (The Urbanophile) recently reposted a blog entry titled, "Migration Matters". Aaron references a number of my ideas and quotes me at length. I take issue with net migration, a statistic I don't find all that useful. A better indicator, I argued, would be inmigration. I wanted the focus to be on talent attraction, not retention.

After working on the Global Cleveland Boomerang Migration project, I've had a change of heart. I still advise against considering net migration. The better metric is gross migration. I'm interested in measuring the talent connectivity between metros.

Gross migration is the aggregate of inmigration and outmigration. Net migration is the balance between inmigration and outmigration. If the net migration is a small number (positive or negative), then you will overlook an important talent trading partner for your metro.

International trade is a good analogy. Some (if not most) people focus on surpluses and deficits. A surplus is good and a deficit is bad. In the United States, big trade deficits get all the headlines. We've got a China problem (Japan before that). As for total trade, you might be surprised to learn that Canada is America's most important partner.

What is the value of that partnership? The balance of trade with Canada won't jump out at anyone. But more consumption in one country will benefit producers in the other. That's reciprocity. The trading of goods isn't a zero sum game.

The same is true for migration. We obsess surpluses and deficits, "brain drain". We ignore reciprocity, or "brain circulation". Such a perspective has a huge bearing on policy.

Yet we do celebrate connectivity, a city's global network of people and businesses. Striving to be a global city is a noble goal. Geographer Peter Taylor is trying to quantify urban globalization. He maps metro trading partners, not the transaction balance. Urban networks matter.

Concerning migration, the same principle applies. Who you know plays a big role in where you go. It is a matter of trust. Canada is close and familiar. That's why the United States trades so much with the Great White North. The apple doesn't fall from the tree for both migration and trade. Proximity is key.

Dense connections between Cleveland and Pittsburgh are normal. The significant exchange of people between Cleveland and a large global city such as New York (on par with Sandusky, OH) is more surprising. Robust churn with Rochester, MN should get your full attention. What's going on here?

The net migration conversation misses all of the above. The bottom line is population, not economic development or urban revitalization. We erect barriers and everyone is poorer for it.

Cleveland talent thriving in Rochester, Minnesota or New York City spells opportunity. There is more inmigration to be had, expatriate or otherwise. You can also use these networks to grow business or encourage more entrepreneurial activity, as Brazil is doing. As much of Peter Taylor's research demonstrates, connectivity with global cities is the lifeblood of an urban economy. Better net migration numbers won't get Cleveland out of the cul-de-sac of globalization.


Anonymous said...

The differences between two metros with similiar levels of inmigration but with otherwise different demographics seems difficult to ignore. Cleveland and cincinnati have had similiar levels of inmigration, yet cleveland has declined by 70,000 in the last decade in metro population while Cincinnati gained 140,000 in that same time. These differences must mean something even beyond the diverging overall levels of economic activity that these demographics imply.

Stephen Gross said...

Regarding Rochester, MN, there's an easy two word explanation: Mayo Clinic.