WASHINGTON – Barack Obama swept to victory as the nation's first black president Tuesday night in an electoral college landslide that overcame racial barriers as old as America itself.The son of a black father from Kenya and a white mother from Kansas, the Democratic senator from Illinois sealed his historic triumph by defeating Republican Sen. John McCain in a string of wins in hard-fought battleground states — Ohio, Florida, Virginia and Iowa.A huge crowd in Grant Park in Obama's home town of Chicago erupted in jubilation at the news of his victory. Some wept.McCain called his former rival to concede defeat — and the end of his own 10-year quest for the White House. "The American people have spoken, and spoken clearly," McCain told disappointed supporters in Arizona.Obama and his running mate, Sen. Joseph Biden of Delaware, will take their oaths of office as president and vice president on Jan. 20, 2009.Mr. Obama, 47, a first-term Democratic senator from Illinois, defeated Senator John McCain, Republican of Arizona, a former prisoner of war who was making his second bid for the presidency. Mr. McCain, 72, conceded the race in a speech to his supporters shortly after 11:15 p.m. Eastern time.