In addition to increases in temperatures expected for all parts of the country, many regions will also experience changes in the magnitude and timing of precipitation. Climate scientists often summarize projected trends with the statement, “wet places will get wetter and dry places will get drier.” These changes are likely to have both positive and negative effects on water-based transportation along rivers, in lakes, and in the oceans.

Increased temperatures, extreme precipitation events, and rising sea levels represent threats to many elements of the United States' land-based transportation system. Extreme weather and climate-related events can damage infrastructure, increase maintenance needs, and interrupt normal operations of roads, bridges, railways, and vehicles. In our fast-paced economy, any disruption of the transportation network can delay the delivery of materials, goods, and people, triggering a cascade of delays and economic impacts across multiple systems.