In 1911, the state of Washington enacted laws allowing people to establish port districts and elect commissioners to administer those districts and oversee their development and operation.In 1921, the Port of Longview was established by a vote of the people residing within the local port district boundary (northern two-thirds of Cowlitz County, from just north of Kalama to the Lewis County line).Originally established as the Port of Kelso, the Port was later changed by a vote of the people, to the Port of Longview, because a state law required ports to be named after the largest city within the district.Original cargo activity consisted of forest products (logs and lumber) exports to Asia. These exports began to decrease in the 1980s, and today are no longer handled by the Port. To replace log cargos, the Port now handles steel, bulk and project cargos.

The Port manages and operates a marine terminal complex where domestic and international ships and barges arrive and depart, and bulk, break bulk and project cargos are loaded or unloaded by local labor union workers. Union workers operate lifting and moving equipment including cranes, forklifts and reach stackers. These workers belong to the International Longshore and Warehouse Union Local 21.Transportation routes connecting to the Port include the Columbia River shipping channel, the BNSF Railway and Union Pacific railroads, and north-south Interstate 5, the main highway running from Mexico to Canada.The Port also leases industrial land and contributes financially towards recreational projects in Cowlitz County.