1. For the population of the average county, 62.8% of friends live within 100 miles.
2. Over distances of less than 200 miles, the elasticity of friends to distance is about – 2.0, and about – 1.2 for distances greater than 200 miles.
3. Conditional on distance, social connectedness is significantly stronger within state lines.
4. “Counties with a higher social capital index have less geographically concentrated social networks.”
5. Social connectedness predicts trade flows, even after controlling for distance, and it also predicts patent citations.
That is all from a new NBER working paper by Bailey, Cao, Kuchler, Stroebel, and Wong. Here is an ungated version.