The Economic Impact of Social Ties: Evidence from German Reunification*
利用1989年柏林墙倒塌，研究发现西德家庭与东德的社会纽带显著提升了个人收入，并促进了区域经济增长，社会纽带集中度高的西德地区人均收入增长更快。
Abstract We use the fall of the Berlin Wall in 1989 to show that personal relationships which individuals maintain for noneconomic reasons can be an important determinant of regional economic growth. We show that West German households who had social ties to East Germany in 1989 experienced a persistent rise in their personal incomes after the fall of the Berlin Wall. Moreover, the presence of these households significantly affects economic performance at the regional level: it increases the returns to entrepreneurial activity, the share of households who become entrepreneurs, and the likelihood that firms based within a given West German region invest in East Germany. As a result, West German regions that (for idiosyncratic reasons) have a high concentration of households with social ties to the East exhibit substantially higher growth in income per capita in the early 1990s. A one standard deviation rise in the share of households with social ties to East Germany in 1989 is associated with a 4.7 percentage point rise in income per capita over six years. We interpret our findings as evidence of a causal link between social ties and regional economic development.