The process for forming a town officially is called incorporation, but towns can exist without that. Take Alaska, for example. The state capital, Juneau, was founded in 1881, but it wasn't incorporated as a city until 1900 because no laws existed to allow a town government.

Now, if you look at older maps, you'll see Juneau on there. You'll also see lots of other towns in Alaska. Town placement is determined by the mapmaker and his or her desires. If you look at a lot of maps of Alaska, you might see a town called Circle, on the Yukon River. It was founded in 1896 and is one of three places where Alaska's road system meets the Yukon River. It appears on lots of maps, yet it has a population of about 100 people.

Deadhorse, Alaska has a population of fewer than 10. It's an industrial town; no one actually lives there. Yet, it's the home of Prudhoe Bay, so you'll see it on maps, too. Importance is a relative term, and maps reflect that relativism.