WASHINGTON (AP) — At the dawn of a new era in race and politics, President-elect Barack Obama practiced the age-old virtue of service on Monday and summoned memories of the Rev. Martin Luther King Jr. “Everyone’s got to be involved,” said the man in line to become the first black chief executive. “Tomorrow we will come together as one people on the same Mall where Dr. King’s dream echoes still,” said Obama, who takes the oath of office at noon Tuesday at a time of economic crisis at home and two wars overseas.