Trump just declared December 26th a national holiday. What’s open and closed?

President Donald Trump’s recent executive order has turned the post-Christmas slump into an official extension of the holiday season, designating Friday, Dec. 26, as a federal holiday. While his directive has effectively shuttered federal offices for a rare five-day weekend, the rest of the economy is operating in a state of partial suspension, leading to a confusing situation about who, exactly, is back to business today.

Trump’s executive order, signed last week, closed executive departments...