The Forest Products Laboratory, in partnership with the Federal Highway Administration and the National Park Service is sponsoring a comprehensive research program on Historic Covered Timber Bridges in the United States. This national program's main purpose is to develop improved methods to preserve, rehabilitate, and restore the approximately 800 timber bridge trusses that were developed during the early 1800's, and still remain in-service today. One of the many ongoing studies is aimed at establishing a procedure for safely and reliably loadrating historic covered bridges through physical testing. Without accurate vehicle load limits posted, these iconic bridge structures would be further damaged and lost for future generations. A total of eleven covered bridges have been load tested and analyzed for structural load capacity within phase one of this study. Three Burr-arch truss bridges were investigated in Parke County, Indiana during 2010; four queen-post truss covered bridges were investigated in the state of Vermont during 2011; and four Howe truss covered bridges were investigated in the state of Indiana during 2012. A new engineering guide manual will provide practitioners with the recommended best practices for analyzing these complex bridge structures in the future.