 A major rating agency has given the state of Minnesota's creditworthiness a boost. Standard and Poor's on Wednesday upgraded its bond rating of Minnesota from double A plus to triple A matching the grade from Fitch. A triple A rating is the highest each agency gives. The nation's third largest rating from Moody's gives Minnesota its second best rating. Those ratings are critical to state and local governments because they allow organizations to borrow money at lower interest rates. State officials credited recent work to shore up $3.4 billion in unfunded pension liabilities for the improvement.