The United States has operated under a two-party system for virtually all of its history.
For elective offices at all levels, state-administered primary elections choose the major party nominees for subsequent general elections. Since the general election of 1856, the major parties have been the Democratic Party, founded in 1824, and the Republican Party, founded in 1854.
Since the Civil War, only one third-party presidential candidate—former president Theodore Roosevelt, running as a Progressive in 1912—has won as much as 20% of the popular vote.
Within American political culture, the Republican Party is considered "center-right" or conservative and the Democratic Party is considered "center-left" or liberal.
The states of the Northeast and West Coast and some of the Great Lakes states, known as "blue states", are relatively liberal.
The "red states" of the South and much of the Great Plains and Rocky Mountains are relatively conservative.
A plurality of Americans identify as Democrats, yet significantly more Americans identify as conservative than liberal.
The incumbent president, Republican George W. Bush, is the 43rd U.S. president. All presidents to date have been white men. If Democrat Barack Obama wins the 2008 election, he will be the first African American president; if Republican John McCain wins, he will be the oldest man to take the office, and his running mate, Sarah Palin, will be the first female vice president.
Following the 2006 midterm elections, the Democratic Party controls both the House and the Senate. Every member of the U.S. Congress is a Democrat or a Republican except two independent members of the Senate. An overwhelming majority of state and local officials are also Democrats or Republicans.
