Whatcom County (WC) owns, inspects, and maintains 162 bridges. WC also provides routine bridge inspection services to other local municipalities (City of Bellingham, City of Lynden, City of Sumas, City of Everson, and San Juan County).
The catastrophic failure of Ohio's Silver Bridge in December 1967, during a pre-holiday rush hour sparked a national program aimed at monitoring the safety of the county's bridges. By 1971, the National Bridge Inspection Standards (NBIS) was issued by the Federal Highway Administration (FHWA). The NBIS established a national policy for uniform inspection procedures and schedules. A 1988 amendment to the NBIS required that all bridges be rated for load capacity and that bridges that do not meet the standard criteria be posted with their restricted load amounts. Load ratings are determined based on the as-built structural elements and the results of field condition inspection, and are performed according to standard practices developed by the American Association of State Highway Transportation Officials (AASHTO).