Some local products are available in all cities, large and small. If the per-capita demand for a product is large relative to the scale economies associated with producing it, even a small city will generate sufficient demand to support at least one firm. For example, it takes just a few thousand people to support a barber, so even a small city will have at least one barber. Similarly, a pizzeria can be supported by a few thousand people, so even a small city will have pizzerias and pizza workers. Of course, a larger city has more hair to cut and more people to feed, so it will have more barber and pizza tosser. In fact, we expect the number of barber and pizza tosser to increase proportionately with city size.