These are examples of causes quite apart from the economic considerations and Cooley has shown that among these forces transportation is the most important, if we look at the question from the point of view of location. Thus, Cooley related the primary reasons for location of cities form the point of view of transportation. He begins with the observation that:

“Population and wealth tend to collect wherever there is a break in transportation”

Cooley explains that by a break is meant an interruption of the movement at least sufficient to cause a transfer of goods and their temporary storage. If only physical interruption of the movement takes place, it is called a mechanical break. But if on account of the close relation between transportation and exchange already pointed out, the physical interruption causes a change in the ownership of the transported goods, it leads to a commercial break.