One of the four vertical struts in the 1232-foot long Paseo Suspension Bridge fractured on January 22, 2003. Fatigue in normal conditions, overstressing and thermal contraction as a result of frozen pin conditions, as well as reduction in fracture toughness at low temperatures were identified as four relevant factors. To ascertain the most likely reason(s), material, fatigue, aad fracture tests were performed on samples of the strut material while the bridge and strut were analyzed under service loading conditions. Numerical results and test data indicated that fatigue was not the primary reason for the fractured strut as supported by the visual inspection done two months prior to the incidence and the presence of a rough fracture surface. It was the mechanically frozen pin condition at the lower end of the strut that resultedinm an unexpected benduig stress and thus sudden to salt and sand accumulation in the strut housing. Low temperature was a contributing factor. An engineering lesson learned from this incidence was that the original design did not allow for routine maintenance without disassembling the fink housing system.