Gap, where the present SR 70 merges with the old road (Dark Canyon Road) that was used before the Feather River was dammed to create Lake Oroville in the 1960s. After crossing through Jarbo Gap, SR 70 drops down into the canyon of the North Fork Feather River, which it follows almost to Quincy, usually on the opposite side from the Feather River Route; this results in two places where both transportation lines cross the river and each other. The first of these is the Pulga Bridge, an arch bridge that crosses over a lower railroad truss bridge; soon after are the highway's three tunnels through rock formations in the canyon. After a fair distance through the canyon, and that formed by the East Branch North Fork Feather River, SR 70 reaches the junction with State Route 89 near Paxton; Routes 70 and 89 overlap southeast from that point, where the East Branch splits into Indian Creek and Spanish Creek. The highway heads southeast, partly along the latter creek, past Keddie to Quincy in the American Valley. It leaves the valley via Greenhorn Creek, passing the Feather River Route's Williams Loop and then following the small Estray Creek to Lee Summit, which the rail line passes under in the Spring Garden Tunnel. This brings SR 70 into the valley of the Middle Fork Feather River, which takes it southeast to Blairsden, where the State Scenic Highway ends and State Route 89 splits to the south, and then east, through the Plumas National Forest, to Portola and Beckwourth. The large Sierra Valley begins at the latter community, and SR 70 heads almost directly across, passing the north end of SR 49 at Vinton and the south end of SR 284 at Chilcoot before crossing Beckwourth Pass, which the railroad takes the Chilcoot Tunnel under, and descending slightly to end at U.S. 395 at Hallelujah Junction. The portion of SR 70 west of State Route 89 near Blairsden is also eligible for the State Scenic Highway System, but has not been designated as such by Caltrans. The entire route is part of the California Freeway and Expressway System, though it is mostly two lanes. SR 70 south of SR 149 is part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration. All of SR 70 is