The Port District covers the geographical western third of the county. Its borders are the county lines to the north, west, and south (the Columbia River) and an imaginary line running from the Columbia River to the north county line just east of Wahkiacus. However, with 12,276 residents and 7,087 registered voters (in 2009), the Port District represents approximately 60% of the county's 20,377 residents and 12,176 registered voters.
The Port District is divided into three commissioner districts, the elected representatives of which form the three-member Port Commission. District #1 represents approximately 3,940 people in the voting precincts of Bingen, Fruit Valley, the southeastern part of North Fruit Valley, North White Salmon, and White Salmon. District #2 represents approximately 3,860 people in the voting precincts of Appleton, East Klickitat, East Lyle, High Prairie, Lyle, the southern part of Mountain Brook, North Dalles, River, and West Klickitat. District #3 represents approximately 3,900 people in the voting precincts of Glenwood, Husum, the northern part of Mountain Brook, the northern part of North Fruit Valley, the northwestern corner of Pine Forest, and Trout Lake.