In South Dakota, the median earnings difference between having a bachelor's degree and having some college or an associate degree is $8,509 a year. Sanghwan Kim/Getty Images Having a bachelor's degree often translates to higher earnings. In some states, the earnings gap between four-year degree holders and adults with some college experience is wider. California has a 58.5% earnings gap, while South Dakota's is 17.1%. Getting a four-year college education isn't always worth it for everybody —