Immigrant Communities and Knowledge Spillovers: Danish Americans and the Development of the Dairy Industry in the United States
研究了19世纪丹麦裔美国人社区如何将现代乳制品知识传播到美国农村，发现1880年丹麦人口较多的县后来更专注于乳制品业并采用更现代的生产方式。
Despite the growing literature on the impact of immigration, little is known about the role existing migrant settlements can play for knowledge transmission and the location of industry. We present a case that can illustrate this important mechanism and hypothesize that nineteenth-century Danish American communities helped spread knowledge on modern dairying to rural America. From around 1880 Denmark developed rapidly, and by 1890 it was a world-leading dairy producer. Using a difference-in-differences strategy and data taken from the US census and Danish emigration archives, we find that counties with more Danes in 1880 subsequently both specialized in dairying and used more modern practices.