Fun with small sample sizes: The most extroverted city in the US is Keota, Iowa.
Keota has 1,009 people. The cutoff for being included in this study was, supposedly, 1,000 people.
The top ten cities are listed at the Des Moines register article; they have populations 1009, 1431, 3183, 1000, about 350, 206, 1468, 950, and 249. (Yes, you read that right; a lot of these cities appear to have populations smaller than 1000. I suspect there’s some conflation of “city” and “area served by that city’s post office” going on.)
This is the same effect that I mentioned last week with regard to Amazon’s best-read cities list, and again I wouldn’t be surprised if the most introverted cities are also very small. The Des Moines Register article says that pyco plans to release this list as well.