Libraries — how this layer is made

What you are looking at

Each point is a library — a feature tagged `amenity=library` in OpenStreetMap. 110,701 of them worldwide, drawn as a dot sized by the footprint of the building. This is the largest layer on HueMaps after places of worship.

Click any feature to see what OpenStreetMap records about it — who runs it, and its website. Where it has a Wikipedia article, a short summary is fetched live and shown in your own language; and every feature links to the OpenStreetMap object it came from.

Two colours, and one of them is an exception

The legend has two rows, and the small one is the point of it.

Private — 405 features, 0.37%. Libraries tagged `access=private`: a company library, a monastery collection, a subscription reading room. Every other library on this map is somewhere you could walk into; these are the ones where you could not, and that is the one fact here that changes what you would do.
Access unknown — 110,296 features, 99.6%.

"Access unknown" means exactly that, and not "public". 97.58% of libraries carry no `access` tag at all. Nobody said those doors are open — the tag is simply absent — and a legend row reading "public" would invent a claim about 109,627 buildings at once. What the map is telling you is that somebody marked 405 libraries as private and said nothing about the rest.

The other values on the tag are `yes` (1,916), `customers` (118), `permissive` (108), `permit` (92), `no` (21), and a tail of a dozen more under ten each. None is folded into "private": each is a different condition of entry rather than a synonym, and blurring them would cost the one distinction this legend exists to draw.

Why the map does not colour who runs a library

That was the original plan — public against private operator, the way the colleges and universities layers do it. The measurement stopped it.

Only 14.3% of libraries record an operator type at all — 16,099 of them. Among those that do, the answer is nearly always the same one: about 13,000 publicly run against about 400 private. A legend built on that would have drawn 86% of the map in "unknown" and, of the rest, 97% in a single colour. Its entire content would have been libraries are usually public, which you already knew.

Drawing a layer finer than its data supports is a way of implying precision that is not there. The operator is shown when you click a library instead, where the same fact is honest one feature at a time: this library is run by that council, and no claim is made about the ones nobody has tagged.

The difference between that and the private class above is not size but usefulness: a rare answer a reader can act on earns a colour where a common answer they cannot does not.

Where libraries are thickest

Counted crudely — features inside a bounding box, per million people — this layer's ranking is unusual on HueMaps, because it broadly agrees with what is known about library provision rather than mostly tracking how keen the local mappers are.

Czechia — 231 per million people, 2,523 in total
Finland — 198 per million, 1,111
France — 175 per million, 11,961
Sweden — 156 per million, 1,651
Poland — 151 per million, 5,533
Italy — 122 per million, 7,205
Germany — 98 per million, 8,126
United Kingdom — 61 per million, 4,202
United States — 61 per million, 20,557
Japan — 30 per million, 3,761
China — 6 per million, 8,701
India — 5 per million, 6,612

Czechia and Finland at the top is not an accident of mapping. Czechia has a library in a very large share of its municipalities, a legacy of a law that required one; Finland's public library system is among the most used in the world. In absolute numbers the United States holds the most, with 20,557.

Kerala is the striking case. That one Indian state holds 4,363 of India's 6,612 mapped libraries — about two thirds of the country's total, on roughly 2.5% of its population. Kerala's library movement has been building village reading rooms for the best part of a century, and the state council registers thousands of them. The densest single view on this whole layer is not a capital city: it is the belt running through Kerala and western Tamil Nadu, with about 2,800 libraries in one zoom-7 tile.

Read all of this as evidence rather than proof. These counts are what has been mapped, not what exists. The ranking agreeing with what is independently known about Czech and Finnish libraries is a reason to trust it further than most of this site's density figures — not a reason to treat it as a survey.

Three features in five are a point, not a shape

60.6% of this layer has no footprint at all. Only 43,617 of the 110,701 features are traced as an outline.

The size of a dot is therefore mostly not telling you how large the library is. Most dots are drawn at one nominal size, set at the median of the ones that do have a shape. Where a feature genuinely is traced, its size is real.

Unlike the art galleries layer, though, these points do not pile up on one another: a library is normally a building of its own rather than a unit inside somebody else's, so untraced libraries sit apart rather than stacking. The densest zoom-16 tile on earth holds 31 of them, in central Rome, and only two tiles anywhere hold more than twenty. That is why this layer stops at zoom 16 where the galleries and embassies layers go deeper.

What counts as a library here

Everything a mapper tagged `amenity=library`, which is a wider set than "the public library on the high street":

Public libraries — the great majority, and the reason for the density figures above.
University, college and school libraries where they were mapped separately from the campus.
National libraries — the Bibliothèque nationale de France, the National Library of China, and their equivalents.
Specialist and institutional libraries — law, medicine, a company archive, a monastery.

Street book exchanges are not here. A book swap in a phone box or a cabinet on a wall is `amenity=public_bookcase`, a different tag, and it is excluded — there are a lot of them, and folding them in would have turned a map of libraries into a map of two different things.

Mobile libraries appear only where somebody mapped a stop as a library, which is rare and inconsistent.

One technical exclusion: the selection matches the tag exactly, so a feature tagged `amenity=library;archive` — a library that is also something else — is missed. Multi-value tagging of this kind is uncommon on this tag.

Mapped, not modelled

Each feature is an object a mapper drew, from survey, local knowledge or a building they walked past; nothing here is modelled or estimated, and no national library register has been merged in. Several countries publish complete lists of their public libraries; none of them is used here, so the counts above are OpenStreetMap's own.

Size

Each symbol is sized by the footprint of the feature, in square metres measured on the globe. Symbol area is proportional to that (radius to its square root).

Among the two fifths of features that are traced, the median footprint is 583 m², the 90th percentile 2,656 m² and the 99th 8,829 m². That is a narrow spread by the standards of this site — most libraries really are about the size of a large house or a small civic building.

The largest feature on the layer is not a reading library. The Library of Congress's High Density Storage Facility in Virginia is 404,696 m²: a book warehouse, forty-five times the 99th percentile. The size scale is capped well below it so that ordinary libraries remain distinguishable from one another.

88.7% carry a name.

A picture of the present

Today's map, not a history. OpenStreetMap is edited continuously; this copy is refreshed periodically. Public libraries close and merge more often than the buildings they occupy change, so a library shown here may have shut.

Source and licence

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