The theory of aging holds that the more engaged people are, the more likely they are to be satisfied with life.

This is the functionalist theory of aging. It is similar to traditional structural-functionalism of sociological theory. In such, having a function that a person or object can accomplish increases the utility and worth of the object (or person, in this case). This increase in utility increases the satisfaction, as well.

Dcalifornia they have the most people with 200+ people per square mile