The Nile, a River in the Desert
Stretching about four thousand miles, the Nile is one of the longest rivers on Earth. Unlike most rivers, it flows north, beginning in the highlands of East Africa and ending at the Mediterranean Sea. Along the way it crosses some of the driest land in the world, the Sahara Desert.
For thousands of years, the Nile has been the lifeline of Egypt. Each summer, rain falling far upstream caused the river to swell and spill over its banks. When the water drew back, it left behind a layer of dark, fertile mud called silt. Farmers planted wheat, barley, and flax in this rich soil, and they could harvest enough food to feed a growing civilization.
The ancient Egyptians organized their whole calendar around the river. They divided the year into a flood season, a growing season, and a harvest season. They also used the Nile as a highway. Boats carried travelers, grain, and the huge stone blocks used to build the pyramids, and because the current flows north while the wind usually blows south, sailors could drift one way and sail the other.
Today, the Nile no longer floods the way it once did. In 1970, Egypt finished the Aswan High Dam, which holds back the water in a huge lake and controls how much is released. The dam protects farms from floods and droughts and produces electricity. But it also traps the silt that once refreshed the fields, so many farmers now rely on fertilizer. Like many great rivers, the Nile still gives life to millions of people, but they must keep working to balance its benefits and costs.