United States Numbered Highways

The system of United States Numbered Highways (often called U.S. Routes or U.S. Highways) is an integrated network of roads and highways numbered within a nationwide grid in the contiguous United States. As the designation and numbering of these highways were coordinated among the states, they are sometimes called Federal Highways, but the roadways have always been maintained by state or local governments since their initial designation in 1926.

The route numbers and locations are coordinated by the American Association of State Highway and Transportation Officials (AASHTO). The only federal involvement in AASHTO is a nonvoting seat for the United States Department of Transportation. Generally, north-to-south highways are odd-numbered, with lowest numbers in the east, the area of the founding thirteen states of the United States, and highest in the west. Similarly, east-to-west highways are typically even-numbered, with the lowest numbers in the north, where roads were first improved most intensively, and highest in the south. Major north–south routes have numbers ending in "1" while major east–west routes have numbers ending in "0". Three-digit numbered highways are spur routes of parent highways but are not necessarily connected to their parents. Some divided routes exist to provide two alignments for one route, even though many splits have been eliminated. Special routes, usually posted with a banner, can provide various routes, such as an alternate, bypass or business route, for a U.S. Highway.

San Francisco

San Francisco (/sæn frənˈsɪskoʊ/), officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California and the only consolidated city-county in California. San Francisco encompasses a land area of about 46.9 square miles (121 km²) on the northern end of the San Francisco Peninsula, which makes it the smallest county in the state. It has a density of about 18,187 people per square mile (7,022 people per km²), making it the most densely settled large city (population greater than 200,000) in the state of California and the second-most densely populated major city in the United States after New York City. San Francisco is the fourth-most populous city in California, after Los Angeles, San Diego and San Jose, and the 13th-most populous city in the United States—with a Census-estimated 2014 population of 852,469. The city and its surrounding areas are known as the San Francisco Bay Area, and are a part of the larger OMB designated San Jose-San Francisco-Oakland combined statistical area, the fifth most populous in the nation with an estimated population of 8.6 million.