Load ratings are used in part to allocate federal funding to agencies and to plan for repairing, replacing, and rehabilitating bridges. Therefore, load ratings can affect the movement of goods throughout a region and are vitally important to the continued safe and efficient operation of the highway system. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 571: Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information gathers and synthesizes information on the methods that states currently use to perform load ratings of bridges and culverts with missing or incomplete as-built information and, in doing so, to establish the current state of practice.