In this article, the financial situations of those who cohabit and those who get married are compared. First off, the number of people who cohabit has more than doubled since the mid 1990s. Those without a college education are also much more likely to cohabit than those with college degrees. When the finances of those who cohabit and those who get married are compared, education becomes a major factor. Those with college degrees who cohabit have greater median household incomes than those with college degrees who get married. However, among those without a college education, couples who get married earn a greater median household income than those who cohabit.
Source: Freakonomics Blog