Look for characteristics that these cities have in common.

You should have noticed that the majority of the major cities shown are located either directly next to or in close proximity to a large river or body of water. Water is essential to the survival of a settlement. It provides irrigation for crops so that a permanent society can grow. It provides transportation for movement and trade within the population, as well as between the settlement and foreign groups. It can also be used to defend the settlement or to provide quick escape when threatened. The location of natural resources also influences the settlement patterns.