World Travel City Photography

Also, economies of scale:
(4) I = 4O1 / 2. This equation (solving for I in equation (3)) shows that the same output requires less input.
"Cities, then, economize on protection, and so protection against marauding barbarian armies is one reason why people have come together to live in cities..." (O'Flaherty 2005, p. 13).
Similarly, "Are Cities Dying?", a paper by Edward L. Glaeser, delves into similar reasons for city formation: reduced transport costs for goods, people, and ideas. Discussing the benefits of proximity, Glaeser claims that if you double a city size, workers have a ten-percent increase in earnings. Glaeser furthers his argument by stating that bigger cities do not pay more for equal productivity than in a smaller city, so it is reasonable to assume that workers become more productive if they move to a city twice the size as they initially worked in. However, the workers do not benefit much from the ten-percent wage increase, because it is recycled back into the higher cost of living in a bigger city. They do gain other benefits from living in cities, though.