U.S. Route 199 (US 199) is a U.S. Highway in the states of California and Oregon. The highway was established in 1926 as a spur of US 99, which has since been replaced by Interstate 5 (I-5). US 199 stretches 80 miles (130 km) from US 101 near Crescent City, California northeast to I-5 in Grants Pass, Oregon. The highway is the northern portion of the Redwood Highway. In Oregon, US 199 is officially known as Redwood Highway No. 25. The majority of the road in California is the Smith River Scenic Byway, a National Forest Scenic Byway. The first roadway, a plank road, from Crescent City was established in May 1858, and before the US 199 designation was applied to the highway, the roadway was designated Highway 25 and Route 1.

U.S. Route 99 (US 99) was a main north–south United States Numbered Highway on the West Coast of the United States until 1964, running from Calexico, California, on the Mexican border to Blaine, Washington, on the Canadian border. It was assigned in 1926 and existed until it was replaced for the most part by Interstate 5. Known also as the "Golden State Highway" and "The Main Street of California", US 99 was important throughout much of the 1930s as a route for Dust Bowl immigrant farm workers to traverse the state. Large portions are now California State Route 99 (SR 99), Oregon's Routes 99, 99W, and 99E, and Washington's SR 99. The highway in Washington connected to British Columbia Highway 99, whose number was derived from that of US 99, at the Canada–US border.