Despite the definitive headline, the below list is admittedly inexact—as, I suppose, all lists tracking the movements of large numbers of people in and out of foreign and domestic institutions must be. Not all of the libraries I researched had up-to-date public information about the number of visitors, or any information at all (so these I had to exclude), and there were a few cases where I found competing figures, or press releases in foreign languages. Plus, I admit that I did not research every single library in the world, but only the ones that seemed likely to rank. Now, with all those caveats in place, please enjoy the below popularity contest, and if you’re so moved, nominate your own favorites in the comment section.
New York Public Library, New York, NY, USA: 18 million visitors per year