Who is your town twinned with?

Twinning is one of the quieter success stories of the last eighty years. Two councils sign a charter, exchange visits, name a street or a roundabout after each other, and send school parties and brass bands back and forth. Few people could name their own town's twins, yet together these small agreements form a dense web across the world. I wanted to see that web whole: who is linked to whom, when the links were made, and how far they reach.

Wikidata, the open database behind Wikipedia, records twinnings with a single property ("twinned administrative body"). I took every one of its 55,634 statements, turned them into 29,437 unique pairs of places, and placed each place by its coordinates. About 35% of pairs carry a start date, so the timing stories below rest on that dated third. The map works best as a way to explore your own town: search for it, and its partners light up.

01 · The mapEvery twinning, as an arc

02 · WhenA post-war idea that peaked in 1990

A handful of links in the data are dated before the Second World War, but the habit really starts in its aftermath. Only 75 dated pairs began before 1950. The 1950s added 257, the 1960s 675, the 1970s 765, and then the numbers took off: 1,375 in the 1980s and 2,558 in the 1990s. The single busiest year is 1990, with 298 new dated links, the year after the Berlin Wall fell. Since then the pace has eased but not stopped: 1,921 in the 2010s and 322 so far in the 2020s. Of all dated twinnings, 69% began in 1990 or later.

Start dates are missing for most pairs, and the gaps are uneven: Taiwan has a date for 69% of its links, Switzerland for 14%. The shape of the curve is more reliable than its height.

03 · ReconciliationFrance and Germany, and Coventry

The most common pair of countries in the whole web is France and Germany, with 1,442 town pairs, more than any country has with itself. Of those with a date, the peak decade is the 1960s (152 pairs), and the median start year is 1974. Links involving a French town made up 42% of all new dated twinnings in the 1950s, and links involving a German town 43% in the 1960s; both shares then slid as the rest of the world joined in.

Britain followed the same path on a smaller scale. Of the 1,619 links that involve a UK place, 34% are with France and 24% with Germany; the median start year of the dated ones is 1984. The most-twinned UK places in the data are London (33), Coventry (26) and Sherborne (25).

Coventry's list reads like a history lesson. Its earliest dated link is with Volgograd in 1944, then Lidice in 1947, and by 1963 it had added Warsaw, Belgrade, Sarajevo, Ostrava, Caen, Graz, Dresden and Kiel, among others. Several were behind the Iron Curtain, and one was Dresden, the German city whose wartime bombing is so often remembered alongside Coventry's own.

04 · Across the Iron CurtainLinks between East and West

To look at the Cold War I split places into two camps by their present country: an Eastern bloc (the Warsaw Pact members and the former Soviet republics, plus the five eastern German states) and a West (NATO members as of 1989, the western half of Germany, and the neutral states Austria, Finland, Ireland, Sweden and Switzerland). Of the dated pairs that began before 1990, 15% (469) crossed that line. In the 1990s the share nearly doubled, to 28%, as towns in Poland (167 dated links in the 1990s), eastern Germany (122), Russia (97) and Hungary (86) signed up with partners in the West.

Before 1990 the busiest Western partner was France (101 dated links), then West Germany (97) and Finland (81), a small neutral country with a long border with the Soviet Union.

The most striking case is inside Germany itself. Of the 771 pairs of German towns on Wikidata, 654 join a town in the former East with one in the former West. Most have no date, but of the 117 that do, 36 began before 1990: one is dated 1984, then Saarlouis with Eisenhüttenstadt and Bremen with Rostock in 1986, and a run of others from 1987 to 1989. Another 52 were made in 1990 alone, the year of reunification.

05 · Going globalFurther apart, and the rise of Asia

The first twinnings were neighbours. Of the pairs dated to the 1950s, only 14% crossed between continents, and the median distance was 776 km. By the 1980s, 44% were intercontinental and the median distance was 1,775 km. Across the whole web the median twin lives 1,009 km away; the longest link, Taipei to Asunción, spans 19,929 km.

East Asia was a big part of that reach. Japan has 1,751 twinnings, 288 of them with the United States and 491 between Japanese towns. Its share of new dated links peaked in the 1980s at 21%. China arrived later: it has 1,712 twinnings, led by Japan (232), the United States (146) and Russia (113), and its median start year is 2004. Chinese towns took part in 12% of new dated links in the 1980s and 17% in the 2010s.

06 · The championsThe most-twinned places

Most places are modest twinners: the median place in the data has 1 partner, and 54% have just one. A few collect them. Rio de Janeiro leads with 122, then Saint Petersburg (118), Shanghai (86), Kyiv (86) and Moscow (80). Bethlehem, recorded on Wikidata with about 36,000 people, has 64: more than London (33), Berlin (32) or Paris (24). Only 303 places have twenty or more.

07 · NamesakesBoston and Boston, Perth and Perth

Some towns twin with their own name. I counted 130 pairs where both places have the same name in different countries, most often between the United Kingdom and the United States (20 pairs), the old namesakes of colonial settlement. The UK list includes Boston, Cambridge, Christchurch, Perth (twice, with Australia and Canada), Plymouth, Portsmouth, Salisbury, Stafford and Worcester, and Coventry, which is twinned with three American Coventries. The most repeated namesake of all is Trujillo: the four Trujillos in Spain, Peru, Venezuela and Honduras are all twinned with one another, 6 pairs in all. Choose "Namesakes" above the map to see them all.

08 · 2022The links that were cut

After Russia's full-scale invasion of Ukraine in February 2022, many councils suspended or ended their links with Russian and Belarusian towns. Wikidata records an end date for 254 twinnings in all. Of the 115 that ended in 2022 or later, 90 involve a Russian (80) or Belarusian (10) place. The partner towns were most often in Poland (29), Lithuania (15) and Finland (12).

This is surely an undercount. Wikidata only records an end when an editor adds one, and 1,650 Russian twinnings have no end date at all. Treat these 90 as a documented minimum, not a count.

09 · CheckingHow complete is the web?

English Wikipedia keeps its own lists of twin towns, country by country, written separately from Wikidata. I read all 85 list pages (34,971 partner lines; most pairs appear twice, once in each country's list) and looked for each pair on Wikidata by name. 56% of the lines matched a Wikidata pair; for 74%, both towns were in the Wikidata twinning data under the same name, even if not as a pair. Name matching misses some real matches (spelling, "Municipality" suffixes, districts), so the true overlap is higher, but the gap is real: Wikidata is a large sample of the world's twinnings, not a census.