As with actual siblings, there's no one way to define the relationship.
There's a bit of a sibling squabble breaking out in Chennai, India. Chennai has two American sister cities, Denver and San Antonio, but the relationship exists "only on paper," according to a report earlier this month in the Times of India. City leaders told the Times they had not arranged any recent delegations between the cities, nor had they adopted any civic programs from their far-flung partners.
"Frankly, we do not believe that it enhances our profile," one Chennai official said of the sister cities arrangements.
You're probably vaguely familiar with the existence of "sister cities" — whether through road signs seen when entering a town or flags flown at an international airport — but what exactly does that designation mean? Mary Kane, president and C.E.O. of Sister Cities International, which formally recognizes the partnerships, says that as with actual siblings, there's no one way to define the relationship.
"Sometimes they're just student exchanges, sometimes they're professorial exchanges, sometimes they're medical exchanges, sometimes it's humanitarian systems, and other times it's economic development," says Kane. "But it all starts out with building the relationship."
The international sister cities program dates back to 1956 and the Eisenhower Administration. Recognizing the damage done to diplomacy during World War II, Eisenhower established the program as a civilian vehicle for repairing and promoting international relations. Some of the early partnerships with cities in Germany and Japan represented clear attempts to erase old tensions.
"We're citizen diplomats," says Kane. "Foreign affairs doesn't have to be done just by the State Department. It actually works better if we bring it down to our individual communities and the people in the communities."
The partnerships can form in a number of ways. Often a diaspora community in an American city will take the idea to local leadership. Other relationships evolve out of U.S. humanitarian aid efforts. Capital cities like Washington, D.C., often prefer bonds with other capitals. Some sister cities are bound merely by name—one example being Toledo, Ohio, and Toledo, Spain.
A recent study of sister city agreements (via Samuel Arbesman at Wired) found that geographic distance had only a "negligible influence" on the nature of this network [PDF]. That's very different from personal relationships, where proximity increases the probability of a connection. The researchers go so far as to wonder whether sister cities represent "the first evidence in real-world social relationships (albeit in its institutional form) for the death of distance" in human communication.
That conclusion seems a bit of a reach, but from a strictly geographic perspective some of the relationships are indeed surprising. Take the recent arrangement between the Iowa city of Muscatine and the Chinese county of Zhengding. In 1985, a young Xi Jinping — now president of China — stayed in Muscatine as part of a delegation of agricultural students. When Xi returned to the United States last fall he insisted on visiting his old host family in Muscatine.
"Also, I have to tell you, that Iowa has got a great soy bean deal out of it, too," says Kane.
Outcomes of these sibling partnerships do vary considerably. As a result of its relationship with Spoleto, Italy, the city of Charleston, South Carolina, has a huge Italian festival every year that generates millions of dollars for the local economy. The partnership between Tempe, Arizona, and Regensburg, Germany, inspires an annual Oktoberfest that raises money for student trips. Salisbury, Maryland, has a friendship with Tartu, Estonia, centered around a cyber-security exchange.
Kane says that it's not unusual for things to go dormant — as they have in Chennai — often when a new administration takes office. But Sister Cities International discourages cities from ending agreements just because they don't seem to be working at the moment. For one thing, she says, it can offend the other nation; beyond that, things often pick up again with time.
"It's just going out and finding someone in that community who's interested in restarting or regenerating a relationship," she says.
Top image: A sign indicating the sister cities of Los Angeles, via Flickr user InSapphoWeTrust