Answer this question about a D.C. holiday tradition. Posted at 12:04 PM ET, 12/06/2012 By Answer: Lighting the National Christmas Tree Source: "In November 1923, First Lady Grace Coolidge gave permission. . .to erect the "National Christmas Tree." That Christmas Eve, at 5 p.m., President Calvin Coolidge walked from the White House to the Ellipse [to light the tree].