At some point after World War II, US migration patterns underwent a cataclysmic shift. Public intellectual Richard Florida calls it the rise of the Creative Class. Florida detailing evidence of the transformation:

According to research by Christopher Berry of the University of Chicago and Edward Glaeser of Harvard, in 1970 human capital was distributed relatively evenly throughout the United States. Nationally, 11 percent of the population over twenty-five years old had a college degree, and that figure ranged between 9 percent and 13 percent in fully half of America's 318 metropolitan regions. In Washington, D.C., 18 percent of the residents had finished college; in Cleveland, only 4 percent had finished.

Over the past three decades, the percentage of Americans holding a college degree has more than doubled, reaching 27 percent by 2004, but as the maps below show, those gains have not been evenly spread. For instance, about half of the residents of Washington, D.C., and San Francisco now have college degrees—versus 14 percent and 11 percent in Cleveland and Detroit respectively.

Why did college graduates go from relatively evenly distributed to concentrating in a few winning cities? Like Florida, economist Enrico Moretti doesn't really answer the question so much as he maps the landscape. How America has changed:

This willingness to relocate is a large factor in America's prosperity, and it always has been. Today, about half of American households change addresses every five years, a number that would be unthinkable in Europe, and a significant number relocate to a different city. About 33% of Americans reside in a state other than the one they were born in, up from 20% in 1900.

This staggering degree of mobility has both positive and negative effects. On the one hand, moving has social and personal costs. Compared with Europeans, Americans tend to live farther from their parents and siblings. They are less attached to their neighborhoods and less familiar with their neighbors. But there are also advantages to mobility: If the economic conditions in a region aren't particularly good, Americans tend to look for better opportunities somewhere else. By contrast, Italians and other Europeans tend to stay put. They give up career opportunities and higher salaries to be close to their parents and friends.

Among Americans, however, there are large differences, with some groups much more willing to move than others. At the time of the Great Migration in the 1920s—when more than two million African-Americans abandoned the South for industrial centers in other regions—less-educated individuals were more likely to migrate in search of better lives. Today, the opposite is true: The more education a person has, the more mobile he or she is. College graduates have the highest mobility of all, workers with a community-college education are less mobile, high-school graduates are even less and dropouts are the least mobile of all.

Emphasis added. During the first Great Migration, the working class moved to improve. Over the last half of a century, the Creative Class moves to improve. Moretti better than Florida laments the downsides of that flip in fortune in his book, The New Geography of Jobs. Today's economic era of innovation is radically different from the two previous ones, agriculture and manufacturing. Industry's need for bodies gives way to a demand for brains.

The demand for labor explains a lot of migration patterns. World War I caused a shortage of workers in the industrial North, the driving force behind the Great Migration to Chicago. A recent story at Major League Baseball (that's not a typo) explains:

Many northern industrial companies sent recruiters to the South in search of labor to replenish their war-depleted ranks. For a time, even the federal government tried to entice Southern blacks to move to higher geographic latitudes.

"Blacks were persuaded [to move north] by government agents from the Department of Labor for a very short period [of time] because Southern whites needed blacks in the South to work for virtually nothing," Reed explained. "[The white Southerners] pressured the federal government to stop the official government sanction that had blacks coming north.

"But then the companies that needed workers — the big meat-packing companies and some of the steel companies — they'd send agents to the South to induce workers to come north. And sometimes they had [train] tickets," Reed added.

The rush was on. Millions, most with little education, relocated. For the lower classes, this was their shot at upward mobility. After World War II, those opportunities would dry up.

The transformation from an industrial economy to something else (i.e. Innovation Economy) occurred after World War II. However, not every city jumped into the future. Journalist Scott Martelle, author of Detroit: A Biography, contends that the business leadership failed to diversify the regional economy:

"Just after World War II when the auto industry was retooling from war footing from making tank and armaments back to making motor vehicles, they really had a chance then to change the industrial fabric of Detroit. So they missed a crucial opportunity then."

In his book, Martelle notes the rise of the Pentagon as an economic engine. The war machine in a time of peace demanded brains, not brawn. The country needed more engineers, not Rosie the Riveter.

Just as mechanization had forced many off of the family farm and into the city, the number of manufacturing jobs plummeted while output soared. Where could an unemployed automobile assembly line worker move to find work? The pull elsewhere evaporated. Many stayed put, stuck in poverty. Those who had means and a college education, left. Chicago once again sucked up the wayward talent, the Great Creative Class migration.

Vexing Enrico Moretti are the numbers required to run the Innovation Economy. The demand for the Creative Class in the Chicago Loop isn't anything akin to the mass of humanity needed to staff a meat-packing plant or steel mill. Moretti hails the multiplier effects that innovation jobs generate. But one must move to Chicago in order to benefit from the shortage of restaurant workers feeding the conspicuous consumption of the Creative Class. The table scraps only fall so far from the source.

Whoever moves, wins. Immigrants, who used to be doctors in the home country, will wash the dishes or line cook. Liberal arts majors will serve up lunch martinis to the latest round of twentysomething techies. The Creative Class will cater to the Creative Class in the gated city, protected from the anarchy in the suburbs.

Photo Credit: Talent Migration/shutterstock