This document discusses statistical geography used by the U.S. Census Bureau. It explains that there are two main types of census geography: legal/administrative geography which can change at the will of governing bodies, and statistical geography which is created and maintained by the Census Bureau to have no gaps or overlaps. It provides examples of statistical geography units like census tracts, block groups, and blocks, and how they are nested within each other from country to state to county down to the smallest block level. It also discusses how census tract and block group boundaries are updated over time to maintain comparability while accounting for population growth.

1. Understanding Statistical
Geography
Jim Castagneri
Lacey Loftin
1

2. Overview of Census Geography
Two main types of Census
geography:
• Legal or Administrative
• Statistical
2

3. Basics of Legal or Administrative Geography
• Have a Highest Elected Officials
• Boundaries change at the will of
the governing body
• New geographies can be formed
by a new incorporation
3

4. Examples of Legal or Administrative Geography
• States
• American Indian Reservations
• Counties
• Places
• Congressional Districts
• School Districts
• Voting Districts
4

5. Basics of Statistical Geography
• No gaps and no overlaps
• Boundaries are created and
maintained by the U.S. Census
Bureau
• Are created and updated only
for statistical purposes
• The U.S. Census Bureau is the
geographical data steward for
the U.S. Government
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6. Examples of Statistical Geography
• State
• County
• Census Tract
• Census Block Group
• Census Block
• Census Designated Places(CDPs)
• Census County Divisions
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7. Tribal Statistical Geographies
• Tribal Census Tracts (TCTs).
• Tribal block groups (TBGs).
• Census Designated Places (CDPs).
• Tribal Designated Statistical Areas (TDSAs).
• StateDesignatedTribalStatisticalAreas(SDTSAs).
• Oklahoma Tribal Statistical Areas (OTSAs).
• Statistical tribal subdivisions.
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8. CensusDesignatedPlaces
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9. 9

10. Census County Divisions
10

11. 11

12. Census Tracts
12

13. Block Groups
13

14. Country
State County Tract Block
Group
Block

15. State within the Country
State County Tract Block
Group
Block

16. State
State County Tract Block
Group
Block
48

17. County within the State
State County Tract Block
Group
Block
48

18. County
State County Tract Block
Group
Block
48 453

19. Tract within the County
State County Tract Block
Group
Block
48 453

20. Tract
State County Tract Block
Group
Block
48 453 036000

21. Block Group
State County Tract Block
Group
Block
48 453 036000 1

22. Block within the Block Group
State County Tract Block
Group
Block
48 453 036000 1

23. Block
State County Tract Block
Group
Block
48 453 036000 1 1006

24. Block
State County Tract Block
Group
Block
48 453 036000 1 1006

25. Country
State County Tract Block
Group
Block

26. State within the Country
State County Tract Block
Group
Block

27. State
State County Tract Block
Group
Block
48

28. County within the State
State County Tract Block
Group
Block
48

29. County
State County Tract Block
Group
Block
48 439

30. Tract within the County
State County Tract Block
Group
Block
48 439

31. Tract
State County Tract Block
Group
Block
48 439 001017

32. Block Group
State County Tract Block
Group
Block
48 439 001017 2

33. Block within a Block Group
State County Tract Block
Group
Block
48 439 001017 2

34. Block
State County Tract Block
Group
Block
48 439 001017 2 2036

35. Block
State County Tract Block
Group
Block
48 439 001017 2 2036

36. Tracts over Time
• First used in the 1910 census in some urban areas
• Full coverage in 1990
• Population Growth can require tract splits
• Maintain Comparability
• Numbering
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37. 2000 Census
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38. 2010 Census
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39. 2020 Census
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40. What is TIGER?

41. Digital Network of Lines

42. Live Demonstration
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43. Thank you!
james.d.castagneri@census.gov
lacey.e.loftin@census.gov
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