As a general rule, our British cities have a Cathedral, there are exceptions, but does this apply in the US ?
Far from it. And in US definition varies fairly widely from state to state. For example:
"In Illinois, cities must have a minimum population of 2,500 but in Nebraska, cities must have a minimum of only 800 residents. In Oregon, Kansas, Kentucky, North Dakota, Minnesota, and Iowa, all incorporated municipalities are cities. In Ohio, a municipality automatically becomes a city if it has 5,000 residents counted in a federal census but it reverts to a village if its population drops below 5,000. In Nebraska, 5,000 residents is the minimum for a city of the first class while 800 is the minimum for a city of the second class. The Constitution of Idaho makes no distinction between incorporated towns or cities."
For complete analysis:
http://en.wikipedia.org/wiki/City#United_States
Note for UK:
In the United Kingdom, a city is a town which has been known as a city since time immemorial, or which has received city status by letters patent. In England and Wales, prior to 1907 the criterion was simply the establishment of an Anglican Cathedral. For example the small town of Ripon was granted city status in 1836 to coincide with the creation of the Diocese of Ripon, but also in recognition of its long-standing role as a supplier of spurs to royalty.
Newest cities created in the United Kingdom were in:
2012 (Diamond Jubilee): Chelmsford, Perth and St Asaph
2002 (Queen's Jubilee): Lisburn, Newport, Newry, Preston and Stirling.
2000 (Millennium): Brighton and Hove, Inverness and Wolverhampton.