Christmas has arrived in Washington. With the flip of a switch/push of a button, President Barack Obama lit the National Christmas Tree -- a 40-foot Colorado blue spruce growing on a grassy area near the White House known as the Ellipse. Obama was accompanied by his wife, Michelle, and daughters Malia and Sasha. The tradition dates to 1923, when President Calvin Coolidge presided over the lighting a national Christmas tree. Thursday's event kicks off days of holiday celebrations in the nation's capital.