These are classified in six categories according to their population. Class I towns having a population of 1, 00,000 or more have grown rapidly. There were 24 Class I towns in 1901 having a total population of 6.59 million. The number has gone up to over 300 in 2001 accounting for 139.73 million population. The Class I towns accounted for 25.71% of the total urban population while in 2001 they accounted for 64.89% of the total urban population.
Smaller towns in Class IV, V and VI having population less than 20,000 are more numerous than towns in Class I, II and III. But the share of urban population of towns of smaller sizes has declined sharply from 47.23% to 10.88% .The number of towns in Class II and III together declined slightly from 27% to 24.29% during the same period.
The Class I towns have shown maximum growth, Class II and III have retained their growth rate at the average level. The towns of Class IV, V and VI have shown a decline in growth rate in last few decades.