The identity of the second city of the United Kingdom is a subject of some disagreement. A country's second city is the city that is thought to be the second most important, usually after the capital or first city (London, in this case), according to criteria such as population size, economic and commercial importance, political importance or some cultural criteria. There is no official mechanism by which second city status is conferred on a city, and citizens and civic leaders of rival cities often argue over their conflicting claims.
Birmingham has generally been regarded as the second city of the United Kingdom since around the time of World War I, though some polls and media references have quoted Manchester as the second city (and also as the third city). Other cities in both England and Scotland have at times been considered the second city. For example, Glasgow, in Scotland, was in the past called The Second City of the Empire. During the 19th and early 20th century, the whole of Ireland was part of the United Kingdom. During some of this time Dublin was considered to be the second city.
