Dictionary, Census of Population, 2021
Spatial Data Infrastructure (SDI)

Release date: November 17, 2021


The Spatial Data Infrastructure (SDI) is a repository of integrated spatial and tabular datasets that together form the geographic framework for all of Statistics Canada's data collection and dissemination activities. It is both an internal maintenance database and a data archive whose primary purpose is to facilitate the generation of geographic data products. It contains vintages of the National Geographic Database (NGD), administrative and statistical geographic areas, cartographic support datasets, geocoding support datasets, field collection activity data files, population and dwelling count variables, and other datasets integral to Statistics Canada operations requiring a spatial component.

The SDI supports a wide range of census operations, such as maintaining and delineating boundaries of standard geographic areas (including the automated delineation of dissemination blocks and population centres) and geocoding. The SDI is also the source for generating many geography products for the 2021 Census, such as Cartographic Boundary Files and the Road Network File.

Reported in

2021, 2016, 2011 and 2006 (Spatial Data Infrastructure)
2001 (National Geographic Base)


The data are maintained and stored in the Lambert conformal conic projection based on the North American Datum of 1983 (NAD83). Links to other data holdings, such as the Address Register and postal codeOM files, are incorporated into the database.

Given the enhancements to the SDI, primarily through the integration of improved road network data from the National Geographic Database (NGD), geography products for the 2021 Census allow users to geographically reference census data more accurately when compared to the 2016 Census products (e.g., cartographic boundary files, digital boundary files, reference maps, road network file).

Disseminated products are created with files from the Statistical Geomatics Centre's internal data warehouse (GeoDepot).

Refer to the related definitions of BlockfaceCartographic Boundary Files (CBFs)Coordinate SystemDatumDigital Boundary Files (DBFs)Dissemination Block (DB)GeocodingMap ProjectionNational Geographic Database (NGD)Reference MapRepresentative Point and Road Network File (RNF), and related reference guides.

Changes prior to the current census

For 2001, the internal database was called the National Geographic Base (NGB), which was divided into National Topographic Data Base (NTDB) map tiles.

Date modified: