Defining census geographies: international perspectives

Censuses are about geography: there are far simpler ways to both measure national populations and estimate their overall characteristics in considerable detail. However, the results have traditionally been presented mainly as tables, not maps, with the individual data values associated with place-names, not polygons. Although the most recent censuses have been provided with detailed and sophisticated geographical frameworks via Geographical Information Systems technology, ‘historical’ censuses from as recently as the 1970s are full of pitfalls for the unwary. Most census reports are designed to permit detailed comparison with the previous census, but longer term comparisons are usually obscured by changing reporting units. One consequence is that sub-national analysis of census data tends to be based on comparative statics, not long-run dynamics.