The highway system of California is a network of roads owned and maintained by the state of California through the California Department of Transportation (Caltrans). Most of these are numbered in a statewide system, and are known as State Route X (abbreviated SR X). United States Numbered Highways are labeled US X, and Interstate Highways are Interstate X, though Caltrans typically uses State Route X for all classes.
Interstate Highways and U.S. Highways are assigned at the national level. Interstate Highways are numbered in a grid—even-numbered routes are east–west routes (but the lowest numbers are along Mexico and the Gulf of Mexico), and odd-numbered routes are north–south routes (with the lowest numbers along the Pacific Ocean). U.S. Highways are also numbered in a grid—even numbered for east–west routes (with the lowest numbers along Canada) and odd numbered for north–south routes (with the lowest numbers along the Atlantic Ocean). There are 21 Interstate Highways in California, ranging from Interstate 5 to Interstate 980. There are seven current U.S. Highways including U.S. Route 6 and U.S. Route 395.
California State Routes are managed by Caltrans and designated by the California State Legislature. The state route's signs are in the shape of a miner's spade to honor the California Gold Rush. Each state highway in the U.S. state of California is assigned a Route (officially State Highway Route) number in the Streets and Highways Code (Sections 300-635). Since July 1 of 1964, the majority of legislative route numbers, those defined in the Streets and Highways Code, match the sign route numbers. On the other hand, some short routes are instead signed as parts of other routes — for instance, State Route 112 and State Route 260 are signed as part of the longer State Route 61, and State Route 51 is part of Interstate 80 Business. California County Routes are marked with the usual County route shield, and are assigned a letter for where they are located. For instance, county highways assigned "S" are located in Southern California, ones assigned "J" are found in Central California, and those assigned "A" are located in Northern California.
State Route 70 (SR 70) is a state highway in the U.S. state of California. Connecting Sacramento with U.S. Route 395 (US 395) near Beckwourth Pass (lowest in the Sierra Nevada) via the Feather River Canyon. Through the Feather River Canyon, from SR 149 to US 395, SR 70 is the Feather River Scenic Byway, a Forest Service Byway that parallels the ex-Western Pacific Railroad's Feather River Route. The Beckwourth Trail was the earliest predecessor of SR 70, which was a spur of the California Trail. This was followed by the railroad, mostly built on the route of the trail; a dirt road was needed for construction that was later converted into part of the present state highway. Construction on the highway began in 1928, which involved the boring of three tunnels. Previously, the road was signed as U.S. Route 40 Alternate, crossing the Sierra Nevada at a lower elevation than Donner Pass on US 40, now Interstate 80 (I-80). The road was renumbered SR 70 in the 1964 state highway renumbering. Today, portions of SR 70 have been upgraded to a four-lane expressway, and even a freeway in a few locations.
Interstate 580 on the Richmond–San Rafael Bridge
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