The Mississippi River Bridge in Vicksburg, Mississippi, is a seven-span cantilever bridge that is 1033 m long by 20.9 m wide and is part of the Interstate-20 corridor. On March 23, 2011, at approximately 14:30 CST, a barge moving downstream struck a pier of the bridge. An infrasound array located at the U.S. Army Engineer Research and Development Center (ERDC) detected the impact. Finite Element (FE) models were developed to investigate the structural behavior of the bridge due to the impact. The FE models identified events within the infrasound record that were possibly produced by the different modes of vibration of the bridge structure. The emerging technology of structural infrasound monitoring and the potential for using infrasound as a forensic tool is demonstrated with the results of the bridge-barge collision event and capability of deployment in the future.