> cities are net consumers of food and people but net producers of goods and money (otherwise how would they buy all that food?) Let's be careful with our term

> cities are net consumers of food and people but net producers of goods and money (otherwise how would they buy all that food?) Let's be careful with our terms. Money is produced in the Bureau of Engraving. What you mean is that people within cities earn a higher income, which is true. Urban populations have higher incomes and consumption. But that means that money is flowing into the city from outside. Every time you swipe your credit card, someone in Manhattan gets a cut. Every time you buy an online ad, someone in Silicon Valley takes a cut. When you buy insurance, someone in Hartford takes a cut. Money from all over the country flows into cities. So why does money flow into the city? For the same reason that a marketplace makes money or a platform makes money. It is a schelling point, helping to bridge the gap between intrinsic worth and market worth. The app you wrote is great but it wont make any money without a platform to run on. The baseball player may be a hall of famer but his pay will be determined by the stadium he plays in. Cities are generally where various professionals, managers, and administrators concentrate, and these earn higher incomes as they provide support services or organizational services to the rest of the economy. > If cities were parasitical we'd expect areas with cities in to support smaller populations than equivalently-sized rural areas, which is false I don't mean parasitical in a moral sense, but in the sense of the flow of real quantities (as we are talking about transportation along roads), because the value add of cities is organizational in nature rather than productive in nature. What we see is that if you create a high population rural area, a bigger city will spring up somewhere in the middle of it, just like if there are more producers, a bigger marketplace will emerge to be the focal point of those producers. > why do people go to the city to seek their fortune? Because that is where higher income/higher consumption opportunities lie. Just like why every company wants to be a platform. Or why ambitious corporate types want to be near the HQ. If you are a budding manager or would-be corporate lawyer, do you set up your shingle in Bullhead City, AZ, or in NYC? You want to be where all the money flows so you can be there to receive a cut. That's not to say you are stealing or being lazy. Obviously the competition to get that cut is fierce. > The question we should be trying to answer is: for a fixed capacity of resources how can we support as many people as possible. There is not a single pattern. You need a market place and you need producers to meet in that marketplace. Life is heterogeneous.