Just like plants and animals, cities compete with each other and attempt to take advantage of the local environment in which they find themselves. Some cities are founded on oceans or rivers, others on plains, mountains, deserts or at the crossroads of trade networks. Yet, just like any organism that may find begin itself in an advantageous environment one day and find its environment transformed the next, the fundamental geographic advantages of cities can shift.
Guy Michaels and Ferdinand Rauch examined the shifting fortunes of cities in Europe as Empires ebbed and flowed:
Around the dawn of the first millennium Rome conquered and subsequently urbanised areas, including those that make up present-day France and Britain (as far north as Hadrian’s Wall). Under the Romans, towns in France and Britain developed similarly in terms of their institutions, organisation, and size. Around the middle of the fourth century, however, their fates diverged.
Roman Britain suffered invasions, usurpations, and reprisals against its elite. Around 410CE, when Rome itself was first sacked, Roman Britain’s last remaining legions, which had maintained order and security, departed permanently. Consequently, Roman Britain’s political, social, and economic order collapsed. From 450-600CE, its towns no longer functioned. The Roman towns in France also suffered when the western Roman Empire fell, but many of them survived and were taken over by the Franks.
…Medieval towns in France were much more likely to be located near Roman towns than their British counterparts (Figure 1). These differences in persistence are still visible today: only three of the 20 largest cities in Britain are located near the site of Roman towns, compared to 16 in France.
Cities exhibit a ‘path dependence’, where their fortune is linked to the experience of their specific history. Of course, they can impact their own environment in ways that can manifest physically – such as through the building of canals – or the establishment of trade networks and specialization. They can even spawn the growth of nearby towns to create their own trading microenvironments.