There is a Pew Research study on happiness. It's fascinating stuff, even though it's dangerous to draw any conclusions.
Married people are happier than unmarried people. But, does marriage cause happiness, or do unhappy people have trouble attracting a spouse?
People who attend religious services are happier than those who don't. But once again I wouldn't jump to the conclusion that you can make yourself happy by going to church. More likely, the type of personality that causes lack of religiosity also causes unhappiness.
People who make more money are happier. I am not surprised here at all. However, adjusted-for-inflation income has been rising since Pew began doing this study, but the overall level of hapiness remains the same. It's not money or physical possessions themselves which bring happiness, rather it's doing better than one's peers. This confirms what I wrote in my post on human nature, income, and status.
The study, quite surprisingly, tells us that Republicans are happier than Democrats, and this is true even in a multiple regression analysis in which other correlates of being Republican, including income and religiosity, are factored out. But should it be surprising? I previosly mentioned the connection between guilt and liberalism, and it makes perfect sense that people who feel guilty are less happy.
Are liberals less likely to be married because they are unhappy and therefore have trouble attracting a spouse?