California is America's most populous and wealthiest state, with 55 electoral college votes. It is essential for the Democrats to win here if they have hopes of recovering the White House, but it is an important money centre for both parties.
Yet the election of Republican Arnold Schwarzenegger as governor highlights the tensions in the state between the left-leaning immigrant communities and the famous Californian "alternative" lifestyles on the one hand, and the conservatism which propelled Ronald Reagan to the governor's mansion on the other.
Nevertheless, the state has been going Democrat in recent years and the party won here in the last three elections.
Population: 33,871,648 (ranked 1 among states)
Governor: Arnold Schwarzenegger (R)
Electoral College Votes: 55
But in the 1970s and 1980s, California was a Republican stronghold with voters keen to support fellow Californians Richard Nixon and Ronald Reagan.
California has been a place of opportunity and economic vitality since the Gold Rush and the birth of Hollywood.
The city of Los Angeles, despite no natural resources and no natural harbour, has the nation's largest port and is its second largest manufacturer.
Computer technology is thriving, fuelled by a concentration of venture capital and a large immigrant workforce.
House of Representatives:
33 Democrat, 20 Republican
Senate: 2 Democrat
California has the most urbanised population in the nation, with 94% classified as living in urban areas - more than three-quarters of all Californians live in LA, San Francisco and San Diego metropolitan areas.
But California also has social problems. Although its companies develop some of the world's most sophisticated technology, it has some of the worst elementary and secondary schools in the country.
California's diversity extends to its ethnic mix: successive waves of immigration over the last two centuries have bequeathed it large Asian and Latino populations.
2000: Bush 42%, Gore 53%
1996: Clinton 51%, Dole 38%
1992: Clinton 46%, Bush 33%
This has not come without tension, and in 1996 a referendum was passed which abolished racial preferences in higher education.
This direct democracy process has continued since, with Californians passing propositions on a number of issues. In 2003, this direct democracy process led to the "recall" of Governor Gray Davis.
The fascinating part is pinning down the "real" California. On one hand it wants medical marijuana and alternative lifestyles, on the other it wants strict immigration laws, tough criminal sentences and the abolition of racial preferences and quotas.