Who uses public libraries the most? There’s a divide by religion, and politics.

We scoured all the government sources we could think of before turning to the cabal of polling prodigies over at YouGov to see what they could gin up.

As usual, YouGov exceeded our expectations, asking at least 50 library-related questions of 2,429 U.S. adults in April. The pollsters touched on just about everything: librarian approval ratings, restrictions on drag queen story times, number of books read. They also asked about the library services we actually use, up to and including how many of us avail ourselves of the library restrooms.

The answer to that last question: Apparently, retirement-age folks and Republicans are the least likely to use the library “facilities.” Those of us with advanced degrees are among the most likely to use the restrooms, as are followers of major non-Christian religions.

Why in the world might that be true? Well, for once the answer turns out to be straightforward. The folks most likely to use the loos are simply the top overall library users.

If you think about it, this makes abundant sense. With the occasional exception — shout-out to the lovely Central Branch of the Greater Victoria Public Library in British Columbia, with its convenient downtown location — you’re not visiting the library just to go to the bathroom.

Other top library users — those most likely to visit at least monthly — include adults under age 30, folks who attend religious services at least once a month and Democrats.

What brings these folks to the library? Well, younger adults are more likely than anyone else to go to the library to socialize or browse media other than books. Non-Christian religious folks are more likely than anyone else to go to the library to vote. For the churchgoers, it’s to use library resources: computers, workspaces and archives. Educated Americans gravitate toward the fun stuff: books, classes and children’s programs and help from the librarians.

One thing that doesn’t seem to drive most people to libraries? Financial hardship. In fact, the higher your income, the more regularly you avail yourself of their free books, spaces and services.

And while we can’t say for sure, it seems bookstores and libraries complement each other more than they compete. A near-unanimous 92 percent of Americans with a favorable attitude toward bookstores also have a favorable attitude toward libraries. About 58 percent of U.S. readers get at least some of their books from libraries, and the more you read, the more you rely on libraries.

Of the 17 percent of Americans who read fewer than five books (but not zero) over the past three years, only 22 percent relied on libraries for at least half of their books. On the other hand, 7 percent of you have read more than 100 books since 2021, and you all were about twice as likely to get at least half of them from the library.

Pinpointing the folks who use libraries the most, then, doesn’t beg for advanced data analysis. The people who use libraries just like books. Only 10 percent of non-readers go to the library at least once a month, while almost half of those in the 100-plus-book club do the same.

But what about the folks who use libraries the least? The more we ran the numbers, the more they fell into two loose categories.

The first seemed quickly evident: conservatives. Democrats are almost twice as likely to be monthly library visitors as their Republican friends — 30 percent vs. 17 percent. Southerners, folks 45 or older, Protestants and rural Americans all fall near the bottom of the rankings, and all lean right.

Part of their anti-library stance appears to be ideological. The biggest partisan gaps in the survey come in library funding (31 percent of Republicans want to increase it, compared with 64 percent of Democrats) and ideology. Republicans are twice as likely to say library restrictions are motivated by sincere concerns about harmful material and much less likely to say such restrictions are politically motivated.

They are also much less likely to view librarians very favorably or to consider them politically moderate — though they don’t seem to agree on which way librarians actually lean, pegging them as either more liberal or more conservative.

But then we found a much simpler explanation for the party gaps in library use. They shrink right up when we account for just one variable: the urban-rural divide. About 30 percent of city Republicans visited libraries in the past month vs. 35 percent of city Democrats, a difference that is within the margin of error. For rural folks, the blue-red library gap was 16 percent vs. 9 percent.

Democrats, packed into urban areas, may simply have access to more and better libraries. Rural libraries and bookmobiles are doing secular-saintly work out there with limited budgets. But Iowa’s South English Public Library and North Dakota’s Bowbells Public Library, which serve a few hundred people and measure their budgets in the single-digit thousands, simply can’t provide the exhaustive collection and endless and esoteric services you’ll find at the New York Public Library, which had $332 million to throw around in 2022.

We get those figures from the federal Institute of Museum and Library Services — and we’re only scratching the surface of what they provide. Every year since 1988, the institute, or its predecessors, has worked with state and territorial library agencies to collect data from all the nation’s libraries, a vast network that encompasses about 9,000 public libraries with 17,000 individual outlets.

Even more obviously, Republicans dominate in far-flung rural areas where libraries are just plain harder to get to — 25 percent of Democrats live within a mile of a library, compared with just 14 percent of Republicans, according to YouGov. (Though YouGov’s Carl Bialik points out that could be because Republicans prioritize library proximity less when choosing where to live.)

The second group of library evaders, while more squirrelly to pin down, appear to have something in common. Or, more accurately, they have nothing in common. That is to say, they’re the none-of-the-aboves, united in their embrace of nothing. They “seldom” or “never” go to church. Or their religion is “something else” or “nothing in particular.” Or they follow political news “hardly at all.” Or they’re unemployed. Or they don’t affiliate, even loosely, with a major party. Or they didn’t vote in the last election.

Or all of the above.

Most of those categories overlap, and they seem to build on one another. The more of them you fall into, the less likely you are to go to the library. In contrast with the other library dodgers, many of these groups lean Democratic, sometimes heavily so.

So who are the disengaged? If we’re overgeneralizing, we’d say they’re less educated, work fewer hours and earn less. But they still have a very favorable opinion of libraries and librarians, think libraries are very important and want to increase their funding. They just don’t visit them. Or read much.

Maybe these folks just love pounding that “no” button when they take surveys. But given the diversity of responses, we can’t help imagining that a deeper factor is at play — that going to the library is a decent signal of your broader engagement with society.

Hi there! The Department of Data still seeks quantitative queries. What are you curious about: Which states employ the most librarians? Which libraries have the most bookmobiles? What library branches have the largest footprint in square feet? Just ask!

If your question inspires a column, we’ll send you an official Department of Data button and ID card. This week, we’ll mail cards and buttons to Karen O’Kain in Vancouver, B.C.; Janet, who reads almost exclusively e-books and splits her time between Oregon and California; and Dan Gobble in Greensboro, N.C., who asked what share of the books we read come from libraries. Of the great many readers who asked about libraries, they’re the ones who most directly inspired this column.