Except that the place tag isn't always based on population size. In some places, (e.g. UK), a common cultural definition of a "city" is archaic, and depends if the place has a Cathedral and/or charter from the monarch.
I give you the "city" of St. David's: http://www.openstreetmap.org/browse/node/3216768 It's in Wales, UK, and is tagged as "place=city". It's a small town of ~2,000 people. It has a charter from the monarch, and a cathedral. The "note" tag in OSM says: "the "city" is on paper, what's on the ground is a small town".
Greenhorn, Oregon is designated as a city but has a 2010 census population of zero. Though now unicorporated, Tenny, Minnesota, was a city and had a peak population of 180 people in 1910 but now is down to 5 (2010 census).
I've been playing with place names & http://overpass-turbo.eu/ ... I seem to be getting the best results with "city|hamlet|metropolis|town|village", although some states like Alaska & Hawaii still don't return much with this scope.
In Alaska, a lot of places are labeled as County. In Hawaii, a lot of places are labeled as Other.
I give you the "city" of St. David's: http://www.openstreetmap.org/browse/node/3216768 It's in Wales, UK, and is tagged as "place=city". It's a small town of ~2,000 people. It has a charter from the monarch, and a cathedral. The "note" tag in OSM says: "the "city" is on paper, what's on the ground is a small town".
Humanity is complicated. :)