The map is part of the measurement
Population is counted within boundaries. When a state, district or municipal area changes, its population total can change because the area being measured has changed. Before interpreting a difference as growth or decline, establish that both figures cover the same territory.
The Census of India's Administrative Atlas 2011 describes the administrative structure as it existed on 31 December 2010. It covers 35 states and union territories and 640 districts. Those are the geographic units behind that historical atlas, not a list of India's present administrative divisions. [1]
Andhra Pradesh and Telangana
Telangana came into existence on 2 June 2014, after Census 2011. The original 2011 state-level total for Andhra Pradesh therefore refers to the undivided state. It cannot be presented as the 2011 total for today's Andhra Pradesh without an explanation of how the geography has been adjusted. [2]
The division also involved part of the former Khammam district. This is why simply assigning whole historical districts to the two states can be inadequate for an exact reconstruction. A reliable comparison uses an official table prepared for the required boundaries, or a documented allocation of smaller areas. The resulting figure must say which boundaries it represents. [2]
Changes to union territories
The former state of Jammu and Kashmir was reorganised into the union territories of Jammu and Kashmir and Ladakh on 31 October 2019. A 2011 row headed Jammu and Kashmir in the original state table consequently refers to a different administrative unit from the later union territory of that name. Keeping the same label without a geographic note would conceal that distinction. [3]
Dadra and Nagar Haveli and Daman and Diu provide the opposite example: two union territories were merged with effect from 26 January 2020. A historical table can correctly show them separately. A table organised around the merged territory needs a clear explanation of how its historical figures were assembled. [4]
A boundary change is not population growth
Imagine a district with ten lakh residents being divided into two districts, each containing five lakh. This is an illustration, not an actual district statistic. The population of the original area has not halved. Its residents have been divided between two administrative records. Comparing the old district with only one successor would produce a misleading growth rate.
The same problem affects density. Population and land area must describe the same territory before one is divided by the other. Combining an old population total with a new area figure can create an impressive-looking result that has no consistent geographic meaning. Rankings are also affected when the units being ranked change.
Compare consistent areas
There are two useful approaches. You can preserve each census as a historical snapshot and clearly explain that its boundaries differ. Alternatively, you can reconstruct multiple years on a common set of boundaries, using sufficiently detailed and documented source data. The second approach requires more work; it should not be implied merely by changing a place name.
A city name requires similar care. A municipal area, district and urban agglomeration can describe different geographic coverage. Read the source's definition before putting two totals in the same chart. Similar names alone do not establish that the underlying areas match.
- Check the census year and the boundary date.
- Check whether the unit is a state, union territory, district, municipal area or another defined geography.
- Look for splits, mergers, transfers or reclassified areas between the dates being compared.
- Keep a note of any regrouping or calculation used to create comparable totals.
How to read the historical tables here
PopulationIndia's Census 2011 material should be read as a record of that census and its stated geography. An older administrative name is useful historical context when it is labelled clearly. It becomes misleading only when readers are led to believe that it automatically describes today's boundaries.