WASHINGTON, May 6 (Xinhua) -- Voters in the U.S. state of North Carolina have begun to cast their ballots Tuesday, a critical day for the Democratic presidential nomination race.

    The state has been allocated 134 delegates at the Aug. 25-28 Democratic National Convention, of whom 115 are tied to the results of the primary.

    Polling hours run from 1030 to 2330 GMT, when the first projection of the results will start to come out.

    White and African American voters account for 76.32 percent and 20.07 percent respectively of the state's population. African Americans voters here are expected to give an edge to Illinois senator Barack Obama.

    North Carolina is located on the Atlantic seaboard in the southeastern part of the United States. Its capital is Raleigh.

    It is a fast-growing state with an increasingly diverse economy and population.