This is a list of sister cities in the United States. Sister cities, known in Europe as town twins, are cities which partner with each other to promote human contact and cultural links, although this partnering is not limited to cities and often includes counties, regions, states and other sub-national entities.
Many jurisdictions work with foreign cities through Sister Cities International, an organization whose goal is to "promote peace through mutual respect, understanding, and cooperation." [1]
Twin cities are a special case of two neighboring cities or urban centres that grow into a single conurbation – or narrowly separated urban areas – over time. There are no formal criteria, but twin cities are generally comparable in status and size, though not necessarily equal; a city and a substantially smaller suburb would not typically qualify, even if they were once separate. Tri-cities and quad cities are similar phenomena involving three or four municipalities.