What does the watershed of 1980 mean?

A fork in the road watershed refers to a mountain or highland that separates two adjacent river basins, from which rivers flow in two opposite directions. In nature, there are many watersheds, such as mountains and plateaus, but they can also be slightly undulating plains or lakes. It can also be used to refer to people or things, which means that at 1980, the fate of some people will pass a fork in the road, and their choices will determine their lives.