Why are so many big cities located along the banks of a river?

Since the humans started to have a sedentary lifestyle they have started to build cities. The cities, especially the largest ones have almost always been located along the banks of a river, usually a larger one. This trend has continued for thousands of years and up to the present.

There are several reasons as to why the large cities have built along the banks of the rivers.

In the past, a major reason was the fertile soil, as the larger population needed more food, and the fertile deposits by the rivers enable high scale production of food.

Both in the past and in the present, the rivers have been the primary source of freshwater for drinking, as well as for numerous purposes in the daily lives of the humans.

The rivers were providing water for irrigation, which was crucial in the past.

Both in the present and the past, the rivers have been used for transportation of goods, as well as for travelling.

In more recent times, the rivers are used by the industry, both for its functioning, and unfortunately for the release of waste, and the industry is what drives the economy.

mercury

explanation:

mercury is the least dense because of its size

ask an adult bc this is too hardcore