The Nehalem River is a river on the Pacific coast of northwest Oregon in the United States, approximately 119 miles (192 km) long. It drains part of the Northern Oregon Coast Range northwest of Portland, originating on the east side of the mountains and flowing in a loop around the north end of the range near the mouth of the Columbia River. Its watershed of 855 square miles (2,210 km2) includes an important timber-producing region of Oregon that was the site of the Tillamook Burn. In its upper reaches it flows through a long narrow valley of small mountain communities but is unpopulated along most of its lower reaches inland from the coast.

The Northern Oregon Coast Range is the northern section of the Oregon Coast Range, in the Pacific Coast Ranges physiographic region, located in the northwest portion of the state of Oregon, United States. This section of the mountain range, part of the Pacific Coast Ranges, contains peaks as high as 3,710 feet (1,131 m) for Rogers Peak. Forests in these mountains are considered to be some of the most productive timber land in the world. The Central Oregon Coast Range is directly south of this section with the Southern Oregon Coast Range beyond the central range.