Much of the success of the United States as a nation has had to do with its ability to generate social capital, that mysterious but critical set of characteristics of functioning communities. When your neighbor walks your dog while you are ill, or the guy behind the counter trusts you to pay him next time, social capital is at work. it is the shadow of the future on a societal scale. Individuals in groups with more social capital (which is to say, more habits of cooperation) are better off on a large number of metrics, from health and happiness to earning potential, than those in groups with less social capital. Societies characterized by a high store of social capital overall do better than societies with low social capital on a similarly wide range of measurements, from crime rate to the costs of doing business to economic growth.