A new study confirms what other reports have documented: workers who don't have unions lose out in their paychecks.

The Center for Economic and Policy Research finds [pdf] that the "union premium" is 11.9% for employees nationally -- meaning, those who are part of a union take home almost 12% more in their paychecks each month than those without a union.

If you single out low-wage workers, the boost is even higher: 20.6%.

The findings are especially relevant in the South. Of the 10 states with the lowest number of workers represented by unions, eight are in the South.

The report estimates that in North Carolina -- the state with the lowest rate of union representation -- union membership boosted the wages of low- to middle-income workers by between 11% and 14% from 2003 to 2007.