The official campaign for America's 48th presidential election begins today, with President Carter in his native South and Ronald Reagan wooing Democratic voters in the industrial East.

Carter will marshal Democratic forces with a "relatively brief" speech to an expected 15,000 people at the Big Spring Park Labor Day celebration in Tuscumbia Ala.

Tuscumbia is headquarters of the Knights of the Ku Klux Klan, and Grand Wizard Don Black promised a "show of strength," but police have warned klansmen not to march.

Press Secretary Jody Powell said yesterday that Carter's speech will review not only his administration's peace-keeping acomplishments, but its plans to bring the nation a revitalized economy.

Reagan will fire his opening Republican salvos at Liberty State Park, in the heavily Democratic New York-New Jersey area -- and close enough to the Statue of Liberty and the Manhattan skyline for camera angles.

Reagan then will fly to Detroit for another appeal to the working-class voters he needs in order to win the election.

Reagan will base his appeal to workers on his own conservative terms, arguing that the liberal Democratic Party' philosophy of big government programs has brought high taxes and few solutions to America's problems.

Independent candidate John B. Anderson beat the opening gun yesterday, formally undertaking his giant-killer effort with a speech in his hometown of Rockford, Ill.