While there is no doubt that competing in the workforce with a bachelor’s degree rather than a high school diploma is an advantage, the extent of that advantage varies greatly by state, according to a new study whose findings appear in Change Magazine.

The study, be researchers Matt Crellin, Patrick Kelley, and Heath Prince, finds that college grads in Connecticut aged 25-64 earn an average of almost $70,000 per year, while high school grads in the same age group earn an average of about $30,500, considerably less than half as much.

On the other hand, college graduates in Montana earn about $41,000 a year versus approximately $25,000 a year for high school grads, about 60 percent of what college grads make.

The national average in 2009 was $24,300 for high school graduates and $53,200 for those with bachelor’s degrees.

The states with the biggest advantage for college degree holders are Connecticut, New Jersey, Maryland, New York, Massachusetts, Virginia, California, New Hampshire, Illinois, Texas, Minnesota, and Delaware–all of which have an income difference that is higher than the national average.

The states with the least advantage for college degree holders are Montana, Idaho, South Dakota, Maine, West Virginia, New Mexico, Mississippi, Utah, Wyoming, and Oregon.

Of course this does not mean that degree holders from these and other states are limited to the earning levels in their own states.  But if states do not have employers that require large numbers of college graduates, they are at greater risk of losing home-grown college grads to other states.

Citing another study, the article in Change predicts that by 2018, some 63 percent of jobs in the U.S. will require a post-secondary credential, though not necessarily a bachelor’s degree.  The percentage of these jobs will vary, from 42 percent of jobs in West Virginia to 70 percent of jobs in Minnesota.