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)

May 16, 2007

Outline

Background

The project

The result

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.

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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

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EA-level aggregate statistics have been produced and disseminated by Statistics Canada since 1961

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

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Demand for historical census data revitalized with release of each new census

Requests for historic aggregate census data at UT/DLS, by census year

010203040506070

2006

-200

7

2005

-200

6

2004

-200

5

2003

-200

4

2002

-200

3

2001

-200

2

2000

-200

1

1999

-200

0

1998

-199

9

1997

-199

8

1996

-199

7

1995

-199

6

1994

-199

5

1993

-199

4

1992

-199

3

Academic year

File

s 1961

1971

1976

1981

1986

1991

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STC has previously done tests of: Calgary – 1981 census Kitchener-Waterloo – 1981 census Québec – 1981 census

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)

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

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

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)

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

Inadequate and varying quality of scansCluttered with secondary features (lines, labels, grid, etc.)Dashed linesAll made successful automated vectorization extremely difficult

Scope of changes: 1976-1981

Extent of changes in Regina and Saskatoon 1976-1981

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)

Where does the project go from here?

Whatever Paula Hurtubise said this morning………..

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