About YearMaps

What YearMaps is

The site has two halves. The geographic half is a gazetteer: a page for each of 225 countries and territories, 442 states and provinces, 7,343 cities, and several thousand physical and built features. The historical half is a catalogue of 1,612 polities, from early states to modern empires, each with the years it existed and, where the data allows, the territory it held.

Every page is generated from open datasets rather than written by hand. The data pages carry measured facts such as population, area, elevation, height or channel depth. Where a matching Wikipedia article exists, a short summary of it is shown with a link to the full article. The methodology page explains how this is done and where it can go wrong.

What you can do with it

• Look up a place. Start from a country, move to one of its states or provinces, and from there to its cities, mountains, lakes, dams and ports.
• Compare places. The rankings order countries, cities, dams, mountains, lakes, islands and other features by a stated measure, and each country has its own tables.
• Browse by part of the world. The continent and region pages gather the countries of each region with their main cities and physical features.
• Follow a period. The empires and states catalogue and the eras give the chronology, and the map on each page shows where it happened.
• Check a source. Detail pages end with a note on where their data comes from, and the full list with licences is on the data sources page.

How it differs from a conventional atlas

A printed atlas is a set of maps with an index. A place appears as a label on a sheet, and what the reader learns about it is mostly its position. In YearMaps every place is written up with what is known about it. A dam has its height, river, reservoir and year of completion; a harbour has its channel depth and tidal range, on the page of its sea; each of the 7,343 mapped cities is listed with its population, region and role on its country's page. The map is one part of the page rather than the whole of it, and every page without a map of its own opens the live map on its subject.

The second difference is time. A conventional atlas shows the world at its date of printing, and a historical atlas shows past borders without reference to what stands there now. YearMaps is designed to join the two, so that a historical polity can be read against the modern countries its territory covered, and a modern place against the states that once ruled it.

The third difference is that places which are too small or too thinly documented for a page of their own are still listed. A small town or minor harbour appears as a row in its country's tables instead of being left out.

What the atlas covers

The figure beside each section is the number of entries with a page of their own. It is a count of what the source datasets contain, not of everything that exists: the atlas lists the dams, peaks and ports that its sources record, which is a selection of the world's total.

Where the information comes from

YearMaps does not carry out original surveys or historical research. It assembles published open data and summarises Wikipedia articles under the Creative Commons Attribution-ShareAlike 4.0 licence. Each dataset and its licence is listed on the data sources page. The pages are produced by software from those sources. They are not individually reviewed by subject specialists, and the site makes no claim that they are.

The site is not affiliated with, or endorsed by, the Wikimedia Foundation or any of the projects whose data it uses.

Accuracy and corrections

Because the facts are taken from named sources, an error on a page usually has one of two causes: the source itself is wrong or out of date, or the atlas has matched or grouped something incorrectly. The methodology page lists the known cases of the second kind, such as features near a border being assigned to the neighbouring country.

Where the source is wrong, the lasting remedy is a correction at the source. Wikipedia and Wikidata can be edited by anyone, and a correction made there reaches YearMaps when its data is next rebuilt.

Get in touch

Spotted an error, or have an idea for a map or feature you would like to see? Write to us on the contact page or send a suggestion through the feedback form.