By plane
Flying may be a more reasonable option from crossing large expanses of the state. Many major like American and United and low fare airlines like jetBlue and Southwest link cities within the state of California.
The primary airports are
San Francisco Bay Area--San Francisco, Oakland, San Jose
Los Angeles area--Los Angeles International LAX, Burbank Bob Hope, Orange County John Wayne, Ontario Inland Empire doesn't get a movie star, and a small airport at Long Beach
San Diego
Sacramento
Reno, Nevada for the Lake Tahoe area
Fresno
The busiest second tier airports are Santa Barbara and Palm Springs.
By train
The state's various rail services provide a cheap and reasonably comfortable way to see and get around much of the state. Amtrak (http://www.amtrak.com) operates a few long-distance routes through and out of California visit this Wikitravel article for more information, as well as the three Amtrak California (http://www.amtrakcaliforn...) routes: the San Luis Obispo-Los Angeles-San Diego Pacific Surfliner, the Oakland/Sacramento-Bakersfield San Joaquins which have connecting Thruway bus service to Los Angeles', and the San Jose-Sacramento Capitol Corridor.
In addition, there are several commuter and regional services in the state's metro areas: Caltrain (http://www.caltrain.com), Altamont Commuter Express (http://www.acerail.com/) and BART (http://www.bart.gov/index.asp) operate in the Bay Area, Metrolink (http://www.metrolinktrain...) runs throughout the Los Angeles region, and the COASTER (http://www.gonctd.com/coa...) runs along the coast of San Diego County. There are also light rail systems in San Diego, Los Angeles, San Francisco, Sacramento, and San Jose.
By bus
The bus is not the most glamorous way to get around the state, but it can be the cheapest. Greyhound serves about 100 locations statewide, though these are not all actual stations, some are merely stops. In general, Greyhound serves the same routes that Amtrak does, though in some cases the dog is cheaper, faster, or more frequent. There's fairly frequent service between San Francisco and Los Angeles, San Francisco and Sacramento, and Sacramento and Los Angeles. There's hourly "clocker" buses between Los Angeles and San Diego. The bus stations in San Francisco, Sacramento, and San Diego are all well-located, but in Los Angeles the station is over a mile east of the downtown core. On the other hand, the Santa Barbara Greyhound station is immediately behind the very upscale Saks Fifth Avenue store!
By car
In addition to interstates and U.S. highways, California has one of the most expansive state highway systems in the United States. As with all trips in the United States, a car is usually the best way to get around and see all destinations. However the trip from the top of California to the bottom can take well over ten hours. The coast route State Route 1 and U.S. 101 is much slower and windier than Interstate 5, and GPS travel estimate times may be inaccurate - especially on Highway 1.
Most California drivers are courteous and careful although speeding is rampant, and the safety and ease of driving in California is comparable to most First World industrialized countries. Exceptions may be found in the most congested areas of San Francisco and Los Angeles, where road rage, reckless driving and red-light running are commonplace.
California uses the MUTCD Manual on Uniform Traffic Control Devices lane marking system standard throughout the United States, in which dashed white lines divide lanes of through traffic and yellow divides opposing traffic with single dashed indicating passing and double solid indicating no passing. In many urban areas the lane markings are replaced by Botts dots for additional tactile feedback when crossing lanes.
The network of freeways in major population centers is often confusing and intimidating to those unfamiliar with the area ,so having a good map is very helpful. Almost all exits from freeways are on the right. At interchanges between freeways, in most cases, the flow of traffic continues through the left lanes with the transition to the other freeway being in the right lanes.
Note that at certain freeway interchanges, Caltrans is notorious for posting advance direction signs that do not correctly explain which lanes correspond to which ramps. Additionally, Caltrans does not always consistently post signs warning of upcoming lane drops or merges.
For example, where a freeway has three through lanes and the central lane splits into two lanes, thus resulting in two ramps with two lanes each, the advance signage may incorrectly imply that only the right lane will break off for the upcoming right-side ramp, thus causing visitors driving in the middle lane to merge unnecessarily into the right lane. And the two lanes on the right-side ramp may suddenly merge into each other without any warning.
These issues frequently result in tourists making wild last-minute lane merges. The 2009 national MUTCD is intended to remediate this problem as seen in California and several other states by mandating the use of detailed arrows on direction signs that clearly show which lanes split into new lanes at upcoming interchanges, but California has not yet implemented the new MUTCD standard. Thus, one should always approach major freeway interchanges in California with caution.
Mile-based exit numbering is currently in progress but is still very erratic in areas; an exit number may not be marked at all, may be marked on the last directional sign before the exit, or may be marked on the final "EXIT" sign itself where the exit ramp separates.
Most highways are freely accessible, although there are a handful of toll roads in Orange County, Riverside County, and San Diego. All major bridges in the San Francisco Bay Area have toll plazas on traffic in only one direction. All California toll plazas have cash lanes. Cash toll lanes are usually manned by human toll collectors, but some of the Orange County toll roads use only vending machines in the cash lanes which accept bills and coins. California toll plazas do not have "exact change" lanes where drivers may toss change in a basket. All California toll plazas also have lanes for FasTrak electronic toll collection transponders which can be used throughout the state. FasTrak is not compatible with any other state's ETC system. Driving through a FasTrak-only lane without a transponder or an active FasTrak account will result in a very expensive ticket. All toll bridges and toll roads have signage for a "last exit before toll," which you should take if you do not have a FasTrak transponder or enough cash to pay the toll.
In major metropolitan areas, the access ramps to a freeway may have two lanes, one marked with a diamond and the other with a traffic signal. The diamond lane called the "carpool lane" is for vehicles with two or more persons and motorcycles. Vehicles with a single person must use the lane with the traffic light. During high-traffic times, the traffic light spaces out the vehicles attempting to merge onto the freeway. Be sure to read the sign below the light as some ramps allow two or three vehicles per green. A few interchanges between freeways are now using controlled access lights to lighten the gridlock at interchanges.
Some freeways have a high occupancy vehicle HOV lane located along the center divider. This lane, also called the carpool lane, is marked by signage on the wall separating the two sides of the freeway, and in Southern California is additionally marked by a double-yellow line. In most cases, this lane is for two or more persons per vehicle. Some carpool lanes in Northern California are in effect during rush hour only, and a few selected areas, notably in the Bay Area, require three or more per vehicle, so check the signage before entering a carpool lane. Motorcycles may also use carpool lanes. Carpool lanes in Southern California are usually in effect 24 hours a day, and have limited access points marked by a dashed white line. These points are the only points at which a vehicle may legally enter or exit a carpool lane, since under the MUTCD, drivers are not allowed to merge across a double yellow line. The minimum fine for unlawful use of a carpool lane is $341.
All persons in a moving vehicle are required to wear a seatbelt and the driver and all passengers can be individually ticketed for failing to do so. Motorcycle riders must wear a helmet. Cellphone users are required to use a hands-free headset if talking on the phone while driving, and texting by the driver is illegal. Unless otherwise signed, right-turns are permitted at red lights following a full stop. If it is raining hard enough to require you to use your windshield wipers, California law requires that your headlights be turned on.
California does not have stationary photo radar cameras like in other countries, and mobile manned photo radar units are rare and still experimental. However, most California police officers do carry radar guns and use them often, and on rural freeways, the California Highway Patrol occasionally flies aircraft overhead to spot speeders and help ground units home in on their positions. Red light enforcement cameras are in use at many urban intersections, but are usually marked only by a single "PHOTO ENFORCED" sign before the intersection. Even more confusing, all approaches to an intersection may be marked with "PHOTO ENFORCED" signs when only one or two actual movements across the intersection are really photo-enforced. The cameras must obtain a clear view of the driver's face and license plate before a ticket may be issued.
California's laws against driving under the influence of alcohol are very strict. The maximum permissible blood alcohol concentration for drivers of noncommercial vehicles is 0.08%; for commercial vehicles, it is 0.04%. All drivers are strongly encouraged to call 911 to report drunk drivers.