With a few notable exceptions, parts of the Bay Area of interest to tourists are as safe as any other major North American city. However, care should be taken in a few areas, when going "off the beaten path" or when traveling through unfamiliar residential areas. While locals and those from elsewhere in California will generally be able to recognize poorer or high crime areas even when unfamiliar with the specific area, the signs of dangerous areas and slums are not always the same as in other American cities, let alone those abroad.
Certain parts of the Bay Area are plagued by high crime rates. The very worst areas are primarily residential/industrial and not much interest to tourists or travelers - these include the Southeastern section of San Francisco Bayview-Hunter's Point, Sunnydale, Visitation Valley, East Palo Alto, West Oakland and much of East Oakland, some parts of Hayward and San Leandro, Bay Point, San Pablo, Central Richmond, the East parts of Redwood City and San Jose, and Vallejo.
However, other high-crime parts of the Bay Area are either in tourist areas or directly adjacent to them. These are generally safe if you stick to high-traffic commercial/through streets even at night, but care should be taken if you park on or detour through side streets, especially at night. These areas include
San Francisco's Mission District, SOMASouth of Market, the Tenderloin/Civic Center, and the Western Addition in San Francisco.
Oakland downtown and around Jack London Square.
San Jose downtown
Berkeley around the University of California Campus.
Even outside of "dangerous" areas, within the major cities San Francisco, San Jose, Oakland and other developed parts of the East Bay keep aware of your surroundings and utilize the same common sense as in any major urban area.
Certain heavily-latino neighborhoods, including the Mission District in San Francisco and many poorer parts of San Jose such as Alum Rock and the East Bay have a high degree of gang violence. While this will not be such an issue in major shopping centers or on busy commercial streets, especially if venturing outside these areas especially into residential or industrial areas, men should be careful to avoid wearing red or blue shirts as these are associated with Norteno and Sureno gang members.
There are also many rough neighborhoods in many of the poorer suburbs throughout the Bay Area: these include but are not limited to the cities of El Cerrito, Pittsburg, Antioch, El Sobrante, South San Francisco, Daly City, Union City, San Rafael, Fairfield, Napa, and Santa Rosa. If in doubt, ask a local if the area is safe.
Be careful to check for ticks (http://www.cdc.gov/ncidod...) after hiking in fields in the Bay Area. There is a high rate of lyme disease transmission in the Bay Area. If a bulls' eye rash develops at the tick bite site, immediately seek medical help and treatment with antibiotics.
