Tamil Nadu, the most urbanised among the large States in India, has witnessed uneven urban growth. The recently released 2011 census data on urban agglomerations shows that, in the last decade, about half of the increase (about 7.4 million) in urban population has mostly occurred in four urban agglomerations: Chennai, Coimbatore, Madurai and Tiruchirapalli. Chennai is now home to a quarter of the State's 34.9 million urban residents.

Chennai urban agglomeration had a population of about 6.56 million in 2001 and it has increased by 2.13 million to reach 8.69 million in 2011. While Coimbatore has registered a growth of about 0.7 million in population, Madurai has witnessed a rise of 0.26 million and Tiruchirapalli about 0.16 million.

Urban agglomeration is a “continuous urban spread constituting a town and its adjoining outgrowths or tow or more physically contiguous growths.” In the case of Chennai urban agglomeration, Chennai, Kancheepuram and Tiruvallur districts are included.

Compared to other larger urban agglomerations in the country, Chennai ranks fourth and it is less than half the size of Greater Mumbai. When compared to Delhi and Kolkata, it is less by about 7.6 and 5.4 million respectively. Coimbatore ranks 16 and Madurai and Tiruchirapalli rank 31 and 51 respectively among the 53 urban agglomerations and cities with million plus population.

However, in terms of growth rate, Chennai exceeds other major urban agglomerations. Greater Mumbai which witnessed 30.47 per cent growth during 1991-2001 recorded only 12.05 per cent growth during 2001-2011. Delhi and Kolkata urban agglomerations too dropped from 52.24 per cent to 26.69 and from 19.60 per cent to 6.97 per cent respectively during the same period. On the other hand, Chennai recorded a growth of 32.5 per cent in the last decade which is about 12.2 per cent more than the 1991-2001 growth rate.

Of the 25 urban agglomerations listed in 2011 census in Tamil Nadu, only four have million plus and three have half a million plus population. The least populated among the urban agglomerations is Vaniyambadi with 1,16, 712 persons.