thumb|300px|Location of [[Punta Arenas, Porvenir, Río Grande, Ushuaia and Puerto Williams in the southern tip of South America.]]

Southernmost settlements are cities, towns, weather stations or permanent military bases which are farther south than latitude 45°S. They are closely related to the Southern Ocean or either the Roaring Forties or Furious Fifties. Antarctic bases are excluded due to not having a permanent population.

Unlike the northern hemisphere, where several major metropolitan areas such as Moscow, Harbin, London, Paris, Seattle, and Montreal are all located north of the 45°N parallel, the only permanently populated areas south of the 45°S parallel are the small and sparsely populated regions of southern Patagonia in South America, the Falkland Islands, and the southernmost tip of New Zealand.

Southernmost city

The southernmost city in the world is mainly a slogan used for tourism purposes to attract visitors to a city as well as the tourists headed for Antarctica. Ciudad (city) is not a legal designation in Chile and Argentina, except for the Autonomous City of Buenos Aires. Currently, three places use this slogan: Ushuaia in Argentina as well as Punta Arenas and Puerto Williams in Chile, with the last being the absolute southernmost town by latitude. There are several more settlements further south but none are considered to be large enough to be classified as a 'city'. The three contending cities are from north to south:

  • Punta Arenas (, population: 123,403), literally in Spanish: "Sandy Point", is the oldest and largest city in Southern Patagonia, at the Strait of Magellan and the capital of the Magallanes and Antártica Chilena Region. It is the largest of the three contenders with around 130,000 permanent residents and it is called the southernmost city by some media outlets. The basis of its claim to be the southernmost city rests on it being larger than Ushuaia, Río Grande, and Puerto Williams, all of which are farther south.
  • Ushuaia (, population: 82,615), the capital of the Argentine province of Tierra del Fuego, is more commonly regarded as the southernmost city in the world due to its sufficiently large population, its infrastructure, and its accepted classification as a city. Ushuaia is located in a wide bay on the southern coast of the island of Tierra del Fuego, on the northern shore of the Beagle Channel; hence, it is further north than Puerto Williams.
  • Puerto Williams (, population: 1,868), located on Isla Navarino, is the southernmost town in the world on the southern shore of the Beagle Channel. It is the capital of the Antártica Chilena Province, one of four provinces located in the Magallanes and Antártica Chilena Region. Puerto Williams is sometimes considered the southernmost city in the world by Chilean media and some large media international organisations,