Post(-Mongol) Roads to Path Dependence

Why do cities emerge where they do? This paper exploits a rule-based transport network in Imperial Russia to study the origins of urban centers. The yams postal system, introduced by the Mongols in the thirteenth century and maintained by Muscovy, required relay stations in regular intervals to change horses, creating an infrastructure grid whose spacing reflected logistics rather than geography or pre-existing settlements. We digitize all stations listed in the 1777 Russian Road Guide along a sample of 15 major routes, and divide rays between consecutive stops into 0.5 km cells. In modern satellite data, cells located at the historical interval where horses were changed are about thirty percent brighter today than neighboring cells before or after that range. The effect is robust to first- and second-nature controls, ray fixed effects, and controlling of pre-1800 settlements, and is absent for the later Trans-Siberian Railway. Additional analyses show that subsequent city growth correlates little with geographic endowments, but was amplified by later infrastructure investments, suggesting that administrative accidents – not natural advantages – seeded some of Russia’s urban geography. The findings illustrate how spatial inequality can arise from arbitrary historical coordination points, with lasting consequences for the distribution of economic activity.