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Creating Historical Digital Census Boundary Maps for  Canada - a pilot project

This pilot project aimed to create historical digital census boundary maps for the province of Saskatchewan at the enumeration area (EA) level for 1976 and 1981. The project successfully produced EA boundary files for Regina and Saskatoon CMAs, but encountered challenges in vectorizing raster maps and incomplete data for other areas.

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Creating Historical Digital Census Boundary Maps for  Canada - a pilot project

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  1. Creating Historical Digital Census Boundary Maps for  Canada - a pilot project Andrey Petrov, Laine Ruus, Data and GIS Services, University of Toronto Presented at CAPDU & IASSIST 2007 (r3)

  2. Outline • Background • The project • The result

  3. Background • The basic building block of all larger census geographic areas in Canada has until recently (1996) been the enumeration area (EA) • EAs are defined as the geographic area canvassed by one census enumerator during the population census • EAs have not been geostatistically stable over time.

  4. Bg contd • EAs are stackable, therefore can cover >100% of the land area • EAs are the smallest geographic area for which census statistics have been released since 1961 • The number of EAs changes from census to census

  5. Bg contd • EA-level aggregate statistics have been produced and disseminated by Statistics Canada since 1961

  6. Availability of census boundary files & reference maps • Reference maps (raster/print) at the EA-level are available for the following census: • 1971, 1981, 1986, 1991, 1996, 2001, 2006 • STC scanned to tiff: 1971-1996 (EAs and urban CTs) • Boundary files (vector files) at the EA-level are available for the following census: • 1981 (at STC, some lost), 1986, 1991, 1996, 2001, 2006 • Canadian Land Inventory EA boundaries from 1971 & 1976

  7. summary of availability: Summary of descriptive and boundary data availability:

  8. Bg contd • Demand for historical census data revitalized with release of each new census

  9. bg contd • STC has previously done tests of: • Calgary – 1981 census • Kitchener-Waterloo – 1981 census • Québec – 1981 census

  10. Our project • Create a historical digital census boundary files for province of Saskatchewan at EA level for 1976 & 1981 (projected to NAD83) • Why Saskatchewan? • simple geometry, only 2 CMA/CAs • modest census-to-census boundary changes • no changes to Representation Order (Federal electoral district boundaries)

  11. Proj contd Objectives • Test alternative methods of re-creating historical EA boundary files • Assess problems and advantages of each method • Evaluate feasibility of extending the project to create a national coverage of historic census maps

  12. Proj contd Resources used: • Canadian Land Inventory boundary files for 1976 (rural boundaries only) • STC digital boundary files of Regina & Saskatoon • Geography attribute files 1976 & 1981 • EA conversion file 1976-1981 • Area master file/road network files • Scanned raster/analog maps of EA boundaries for Regina, Saskatoon, and rest of Saskatchewan, 1976 & 1981

  13. Proj contd Design requirements • Use only existing data available for the entire country • Develop a repeatable, time & resource efficient method • Miminize manual components • Provide GIS-ready digital output • Ensure compatibility with other STC datasets (1996 geographic base)

  14. And the result • Vectorizing from raster maps proved not feasible • Project successfully produced EA boundary files for 1976 and 1981 for • Regina and Saskatoon CMAs • Remainder of the province: • 58 CSDs missing in 1976 • 78 CSDs missing in 1981

  15. Inadequate and varying quality of scans Cluttered with secondary features (lines, labels, grid, etc.) Dashed lines All made successful automated vectorization extremely difficult

  16. Scope of changes: 1976-1981

  17. Extent of changes in Regina and Saskatoon 1976-1981

  18. Resources required • Hardware: minimum 3.4 GHZ processor, 2GB RAM, 80 GV hard drive, 256 MB multi-port video card • Software: ArcGIS 9.x or higher, full package • Wetware: 155 hours, intermediate to advanced GIS skills (average 3.0 to 5.0 minutes per EA)

  19. Where does the project go from here? • Whatever Paula Hurtubise said this morning………..

  20. Project materials • Report: http://www.chass.utoronto.ca/~datalib/hurtubise/ReportStatcanr2_060331.doc • Zip file of all project files, including outputs: http://www.chass.utoronto.ca/~datalib/hurtubise/Saskatchewan_EA_projectr.zip

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