Prof. Kenneth T. Jackson of Columbia University is at least 30 years late with his pronouncement (March 8) that Southern California is not unusual anymore. My marketing research professor at UCLA Extension taught me that back in 1957.
What he did that Prof. Jackson did not do was convert travel distance to travel time: approximately 25 m.p.h. for surface streets and 50 m.p.h. for freeways. It is the time driving that modifies human behavior--not the distance traveled.
Accordingly, 10 miles equals 24 minutes, 9.2 miles equals 22 minutes, but driving time to work is generally accepted to be 20 minutes--on surface streets, not including parking and walking.
Freeways can add about two to nine miles to the distance traveled to work without changing the time traveled. As the average speeds on the freeways and surface streets have decreased over the past 30 years, people have moved closer to work or changed jobs.