Which J.K. Rowling Harry Potter book sold more than 8 million copies in the United States during its first 24 hours?

Harry Potter and the Deathly Hallows sold more than 8 million copies in the United States during its first 24 hours.

The final novel was released on 21 July 2007, with major midnight launch events around the world. Scholastic, the American publisher, reported sales of 8.3 million copies in the United States during the first 24 hours, an average of more than 300,000 copies per hour.

The figure is specifically a first-day United States sales record, not a claim about worldwide lifetime sales. Earlier Harry Potter books also set major publishing records, especially Harry Potter and the Goblet of Fire and Harry Potter and the Half-Blood Prince. The last book’s position as the series finale helped drive exceptional advance orders and launch-night demand.