In 1997, for instance, 74,014 people either moved into or out of Philadelphia, according to the data. In 2008, the number was 94,346, a 27 percent increase. Even so, the overall churn rate—defined here as the number of movements in and out divided by the overall population—was still only 6.1 percent, a lower figure than in many other urban jurisdictions.Figure 6 compares Philadelphia’s churn rate to 14 other large, urban jurisdictions, some of them cities for which IRS data is available (it is not available for most cities), some of them counties containing major cities and some of them combined city/counties. Numbers for New York City were calculated by combining the results of its five counties/boroughs.Philadelphia’s rate of 6.1 percent ranked 11th among these jurisdictions and was below the median of 8.3 percent. Denver, which is a city/county, had the highest turnover rate at 17 percent. Los Angeles County had the lowest at 4.5 percent.
Cook (Chicago) and Allegheny (Pittsburgh) counties were tied for 13th with a churn rate of 5.2%. The reader who passed along the rink found this surprising. I have the same feeling. I think of Chicago as a high churning global city.
I think turnover of talent is vital for any region's economy. I had the impression that churn is a Chicago asset. I predict that Pittsburgh's churn rate will improve. I'm pessimistic about Chicago, a city struggling to grow its numbers of college educated workers.