1. Understanding Census Geography Lisa Neidert McCormick Specialized Training Institute October 28 – October 30, 2009

2. Census Geography

3. Geographic Areas: with 1-year and 3-year data

6. What’s available in the ACS for single year data: via maps  Maps showing counties and places for each state (or the nation)  http://www.census.gov/acs/www/Product s/users_guide/acs_2008_reference_map s.htm http://www.census.gov/acs/www/Product s/users_guide/acs_2008_reference_map s.htm

7. Counties with single year data: ACS 2008

8. Almost all counties: DE, MA

9. Few counties, no places: VT and WY

10. State with American Indian Places: AK, AL, LA, NC, OK

11. Counties with 3-year data: ACS 2006-2008

12. States where all counties are over 20,000  Connecticut  Delaware  District of Columbia  New Hampshire  New Jersey  Rhode Island

13. What geographies are available in the 2006-2008 ACS? http://www.census.gov/acs/www/acs-php/2006_2008_beginner_users_guide.php

14. What’s available in the ACS: via Look-up tables  Geographic entities available for 1-year data (2007) Geographic entities available for 1-year data (2007)  Geographic entities available for 3-year data (2005-2007) Geographic entities available for 3-year data (2005-2007)

15. Not ready for prime-time: census tracts and zip codes  Need 5-year estimates file 2005 – 2009 Available 2010  Annual updates thereafter 2006 – 2010 2007 – 2011, etc.

16. Example Census Tracts for community districts

17. Community District 11: Manhattan, East Harlem

18. Zip codes  Not census geography However, big demand for zip code data  Census Bureau builds ZCTAs via census blocks  ZCTA FAQs http://www.census.gov/geo/ZCTA/zctafaq. html  Fun resource http://en.wikipedia.org/wiki/Zip_code

20. What are PUMAs?  Public Use Microdata areas  Combination of population geographies that sum to at least 100,000 population.  In rural areas, several counties will form a PUMA. In an urban area, a county will be subdivided into multiple PUMAs.  PUMAs do not cross state boundaries

21. PUMAs....  PUMAs do not have good comparability over time (1990, 2000).  PUMA geographies for the ACS are the same as the 2000 boundaries  PUMAs are reasonable substitutes for counties  Smallest geography available in the microdata.

22. PUMAs...  Can be valuable for bypassing geographic restrictions when one wants national information at the county level  Create pseudo counties based on a cross-walk between PUMAs and counties

23. Statistics based on 1-year ACS data Unit is county

24. Statistics based on 3-year ACS data Unit is county

25. Statistics based on 1-year ACS data Unit is PUMA

26. Illinois example: PUMA to county example

27. PUMAs via Maps  Reasonable tool for rural parts of a state  Somewhat unwieldy for urban areas  Multiple maps per state http://usa.ipums.org/usa/volii/2000pumas.shtml

28. PUMAs via text  Describes PUMA composition  By: County County subdivision Place Census tract  http://usa.ipums.org/usa/volii/2000pumas.shtml http://usa.ipums.org/usa/volii/2000pumas.shtml

29. Metropolitan areas  Defined by Office Management Budget (OMB)  http://www.census.gov/population/www/estimat es/metrodef.html http://www.census.gov/population/www/estimat es/metrodef.html  Frey, et. al. “Field Guide”  http://www.psc.isr.umich.edu/dis/census/brooki ngs.pdf http://www.psc.isr.umich.edu/dis/census/brooki ngs.pdf  Users are free to follow own definitions  Census Bureau follows OMB definitions