▁Rat ings ▁Services ▁assigned ▁D ul uth ’ s ▁GO ▁Bond ▁rating ▁to ▁AA ▁in ▁ 2 0 1 4 ▁as ▁compared ▁to ▁AA - ▁in ▁ 2 0 0 8 ▁ ▁and ▁Mo ody ’ s ▁reported ▁an ▁A a 2 ▁rating ▁in ▁ 2 0 1 4 . ▁ ▁D ul uth ▁has ▁also ▁been ▁referred ▁to ▁as ▁an ▁" av iation ▁hub ", ▁with ▁companies ▁like ▁A AR ▁Cor p ▁and ▁Cir rus ▁A ircraft ▁contrib uting ▁to ▁the ▁city ' s ▁economy . ▁ ▁St . ▁Louis ▁River ▁Cor rid or ▁ ▁Since ▁ 1 9 8 7 , ▁the ▁Saint ▁Louis ▁River ▁has ▁been ▁listed ▁as ▁an ▁area ▁of ▁concern ▁by ▁the ▁E PA ▁due ▁to ▁many ▁years ▁of ▁poll ution ▁from ▁industrial ▁and ▁land fill ▁sites . ▁The ▁clean up ▁began ▁in ▁ 1 9 7 8 ▁before ▁it ▁was ▁listed ▁as ▁an ▁A OC ▁with ▁the ▁installation ▁of ▁a ▁waste - water ▁treatment ▁plant . ▁ ▁In ▁ 2 0 0 9 , ▁Mayor ▁N ess ▁organized ▁a ▁St . ▁Louis ▁River ▁Cor rid or ▁Sum mit ▁and ▁brought ▁over ▁ 7 0 ▁st ake hold ers ▁together ▁to ▁develop ▁a ▁compreh ensive ▁vision ▁for ▁the ▁area . ▁It ▁will ▁see ▁another ▁$ 3 0 0 – 4 0 0 ▁million ▁in ▁additional ▁federal , ▁state , ▁and ▁private ▁money ▁to ▁continue ▁the ▁rest oration ▁progress . ▁N ess ’ ▁vision ▁for ▁the ▁St . ▁Louis ▁River ▁Cor rid or ▁is ▁to ▁maintain ▁the ▁clean lin