We model the network of Jewish communities as one way to see whether the effect of Jews on city growth was indeed casual. By examining how Jewish communities expanded we hope to isolate a source of exogenous variation in the presence of a Jewish community.

Jewish network access itself is, of course, correlated with the unobservable characteristics of the city for which it is calculated. To overcome this we adopt two strategies to create valid instruments out of the network access measures. First, we calculate Jewish network access for cities that are only more than a certain distance away from each other. Second, we use information on expulsions to weight our measure of Jewish network access. The intuition behind this is that Jewish expulsions consist of an exogenous “push” factor leading to Jews settling in new cities close to the existing network of Jewish communities. Using these two strategies we obtain similar (though larger in magnitude) effects from the presence of a Jewish community on city growth. This provides further suggestive evidence that the correlation we found in our baseline analysis was indeed causal.

We then divide Europe into 5km x 5km grids and assign the lowest travel cost to each grid. We apply Djikstra’s algorithm to determine the lowest cost of travel between all 3,211,264 city pairs (van Etten, 2012). This allows us to create a measure of ‘Jewish network access’ for each city.

We assume that a Jewish community is more likely to be established close to another Jewish community because of trade networks, financial relationships, or cultural linkages. We then calculate the closest travel path between Jewish communities using our information about the location of roads and river networks and estimates of premodern transport costs. The important assumption we make is that if cities with Jewish communities share certain “unobservable” characteristics that might make them more likely to grow rapidly, these characteristics become less correlated with distance.

Across specifications, we find that cities with Jewish communities experienced no growth advantage in the 15th and 16th centuries. After 1600, however, they began to grow significantly faster. The relationship we observe in the Figure does not appear to be inline with a pure human capital story. Jews had higher human capital than Christians throughout the medieval and early modern period. But the growth advantage of cities that had Jewish communities only became evident after 1600. This raises the possibility that something else changed around 17th century that made the human capital and skills of Jews more complementary to economic growth. Two Mechanisms: Jewish Emancipation and Market Access

The two factors that stand out in explaining the emergence of a growth advantage for cities with Jewish communities after 1600 but not before are: (1) Jewish Emancipation after 1750; and (2) a complementarity between the presence of a Jewish community and market access.

The process of Jewish emancipation began in continental Europe after 1780. It was a major institutional break that signified a major change in the economic, social, and political status of the Jews in Europe. In work with Jean-Paul Carvalho, I’ve shown that Jewish emancipation lead to a religious schism and the emergence of both Reform and Ultra-Orthodox Judaism.

In the period before Jewish emancipation, legal barriers limited the ability of Jews to put their labor to its highest value use. Jewish businesses were prevented from hiring non-Jewish workers. Jews could not attend universities. Moreover, Jews and Christians were culturally isolated. This changed with emancipation, and we expect to see it reflected in the contribution of Jewish communities to city growth in the post-1750 period.

The second factor we study is the complementarity between the presence of a Jewish community and the development of markets. The historical literature points to the importance of Jewish trading and financial networks. But, while economic historians have conducted numerous studies of market integration during the early modern period, with a few exceptions these have focused on the grain trade with little systematic study of other markets due to data limitations. Jewish merchants in medieval and early modern Europe, however, did not play a prominent role in the grain trade but, rather, were involved in the transport of diamonds, sugar, silks, tobacco, and other luxury products in addition to playing a large role in banking and finance. Therefore, rather than looking at grain markets, we explore a more general measure of market integration based on market access.

Market access depends on the population size of nearby cities weighted by the cost associated with the least cost travel path. We show that market access was increasing for all cities after 1700. We find evidence that cities with Jewish communities were better able to take advantage of this increase in market access. As we detail in the paper, our findings are consistent with the argument made by numerous historians that Jewish trading and finance networks help to knit together the European economy, particularly in the period 1650 to 1800 (Israel, 1985).