This paper considers the heterogeneous microfoundations of agglomeration economies. It studies the co-location of industries to look for evidence of labor pooling, input sharing, and knowledge spillovers. The novel contribution of the paper is that it estimates single-industry models using a common empirical framework that exploits the cross-sectional variation in how one industry co-locates with the other industries in the economy. This unified approach yields evidence on the relative importance of the Marshallian microfoundations at the single-industry level, allowing for like-for-like cross-industry comparisons on the determinants of agglomeration. Using UK data, we estimate such microfoundations models for 97 manufacturing sectors, including the classic agglomeration cases of automobiles, computers, cutlery, and textiles. These four cases – as with all of the individual industry models we estimate – clearly show the importance of the Marshallian forces. However, they also highlight how the importance of these forces varies across industries – implying that extrapolation from cases should be viewed with caution. The paper concludes with an investigation of the pattern of heterogeneity. The degree of an industry’s clustering (localization), dynamism, incumbent firm size, and worker education are shown to contribute to the pattern of heterogeneous microfoundations.

中文翻译：

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城市故事：集聚案例一般告诉我们关于集聚的什么？

本文考虑了集聚经济的异质微观基础。它研究产业的协同定位，以寻找劳动力集中、投入共享和知识溢出的证据。该论文的新贡献在于，它使用一个共同的经验框架来估计单一行业模型，该框架利用了一个行业如何与经济中的其他行业共同定位的横截面变化。这种统一的方法为马歇尔微观基础在单一行业层面的相对重要性提供了证据，允许对集聚的决定因素进行类似的跨行业比较。使用英国的数据，我们估计了 97 个制造业部门的此类微观基础模型，包括汽车、计算机、餐具和纺织品的经典集聚案例。这四个案例——与我们估计的所有单个行业模型一样——清楚地表明了马歇尔力量的重要性。然而，他们也强调了这些力量的重要性在不同行业之间是如何不同的——这意味着应该谨慎看待从案例中进行的推断。本文最后对异质性模式进行了调查。一个行业的集聚程度（本地化）、活力、现有企业规模和工人教育被证明有助于形成异质微观基础的模式。本文最后对异质性模式进行了调查。一个行业的集聚程度（本地化）、活力、现有企业规模和工人教育被证明有助于形成异质微观基础的模式。本文最后对异质性模式进行了调查。一个行业的集聚程度（本地化）、活力、现有企业规模和工人教育被证明有助于形成异质微观基础的模式。