Seaports with access to Physical Oceanographic Real-Time Systems (PORTS®) data move vessels and their cargo more safely and efficiently, and this measure tracks the number of top U.S. seaports that have access to PORTS® data. To create a list of the Nation’s top 175 seaports, NOS selected the top 152 ports by international tonnage, accounting for more than 99.9% of all direct imports and exports by tonnage in 2016. NOS added to this list 23 seaports that are critical to coastal military installations, the Nation’s energy supply, or commercial marine fisheries landings.