The poem, which has been called "arguably the best-known verses ever written by an American", is largely responsible for some of the conceptions of Santa Claus from the mid-nineteenth century to today. Prior to the poem, American ideas about St. Nicholas and other Christmastide visitors varied considerably. On Christmas Eve night, while his wife and children sleep, a man awakens to noises outside his house. Looking out the window, he sees St. Nicholas in an air-borne sleigh pulled by eight reindeer. After landing his sleigh on the roof, the saint enters the house through the chimney, carrying a sack of toys with him. The man watches Nicholas filling the children's Christmas stockings hanging by the fire, and laughs to himself. They share a conspiratorial moment before the saint bounds up the chimney again. As he flies away, Saint Nicholas wishes everyone a "Happy Christmas to all, and to all a good night."

Clement Clarke Moore ( 1779 – 1863) was an American Professor of Oriental and Greek Literature, as well as Divinity and Biblical Learning, at the General Theological Seminary of the Protestant Episcopal Church. Located on land donated by the "Bard of Chelsea" himself, the seminary still stands today on Ninth Avenue between 20th and 21st Streets, in an area known as Chelsea Square. Moore's connection with that institution continued for over twenty-five years. He is the author of the yuletide poem "A Visit from St. Nicholas", which later became famous as "'Twas the Night Before Christmas".