Compared to many countries, Robert Reich , former U.S. secretary of labor for the Clinton administration and a professor of public policy at the University of California, Berkeley, says America doesn't have a strict class structure. If you're born into a low-class family in the United States, he says you can improve your social status by focusing on two factors—income and education.

Generally, Robert says the typical middle-class family earns about $50,000 a year. "Most economists assume that if you are earning, as a family, between $30,000 and $70,000 or $80,000, you're solidly middle class," he says. "Although, it does vary in different parts of the country."

Robert says getting a college education or having a respected profession can also improve a person's class.