Statistical block was the basic geographical unit for census statistics and dissemination until 1999. Henceforth, the basic brick for the dissemination of the renewed census, which begins with the year 2006, is the district IRIS and the statistical block is abandoned.
The statistical blocks are defined by INSEE in consultation with the municipalities.
- In densely built-up areas: the statistical block is usually a single block of houses, possibly divided if a municipal or cantonal boundary runs through the block of houses (or small group of blocks of houses) ;
- In "peripheral" areas: the statistical block is defined by roadways (or other visible boundaries) cutting the area in question into several pieces (more finely than in 1990, but often grouping together several blocks defined by roads).
Blocks may not have any inhabitants (a train station, for example).
A division into statistical blocks was performed at each population census until 1999; we called, for example, "îlots99" -Statistical blocks 99- statistical blocks defined by INSEE for the 1999 population census.