Trade II: Trading Cities

It's pretty easy to define a trading city by fiat. But what if there were a better way? A more consistent way.

Since I have all of the references and cities in a network, and I know how far references can travel and how far their influence reaches, I can directly measure which cities are natural bottlenecks for trade.

There's a couple of ways I can measure this. I can determine the total references flowing through a city. Or I can find out how many individual routes flow through it. Per reference, or simple? Per reference is probably more accurate, but simple (how many routes run through regardless of carriage) is faster. Now, I'm only concerned with how many routes pass through. This will help determine the type of culture the city has - a high volume trade point is politically advantageous.

I need to run some tests to know if that data is even useful, though. Given a scenario where all references are available (even at tiny quanities) to all other settlements, would the trade flow be the same for every city? Even in this case, I don't think so. A city on a river would be found by the algorithm more often than one near the hinterlands.

A truly isolated town may have zero routes (terminal nodes). What are the implications of this? For certain, if you're going there, you're going there, not through it (or you're leaving). That could lend it a certain importance, depending on the size. It may even be a destination settlement. More likely, though, it's a small mining town up in the mountains, probably with no market of its own. Maybe a small trading post for basic goods.

Such towns are cliche starting points for campaigns or stories. The Shire, Two Rivers. Whatever Eragon's village was called. The simple heroes, unspoiled by the modern life of the city. It's good for campaigns, because you can give the players a few sessions to get acclimated to their new surroundings.