It's a two-minute ride. If you don't believe me, ride it for yourself by watching this video.
Anyway, I'm back in D.C. and the escalator was working this morning. But I later discovered on a Google search that it is not the longest escalator in the Western Hemisphere. That title belongs to another escalator on the same line, the one located at the Wheaton station. But Dupont can't be far behind.
Here's a photo:
By the way, there's a very good used bookstore at Dupont Circle: Second Story Books. I've made quite a few "scores" there over the years with books on my National Book Award list for fiction.