The United States has approximately 607,000 bridges on public roads subject to the National Bridge Inspection Standards mandated by Congress. The sudden catastrophic failure of the I-5 Interstate System bridge in Washington State has raised policy concerns in Congress regarding the condition of the nation's transportation infrastructure in general, and in particular the federal role in funding, building, maintaining, and ensuring the safety of roads and especially bridges in the United States. This book discusses highway bridge conditions. It then continues to provide information on a Long-Term Bridge Performance (LTBP) Program that is intended to provide a comprehensive definition of bridge performance that will be the foundation for carefully designed research studies in the LTBP Program.