Census Tract poverty missing values

Hi all,

I’m curious why there are so many missing values for the census tract-level poverty table? I’m using the time series data named [Persons* below Poverty Level in Previous Year]. In addition, there are in total more than 111,000 listed census tracts in that table, isn’t the number of census tracts around 73,000? Thank you!

The NHGIS time series for poverty data are nominally integrated:

Nominally integrated tables link geographic units across time according to their names and codes, disregarding any changes in unit boundaries. The identified geographic units match those from each census source, so the spatial definitions and total number of units may vary from one time to another (e.g., a city may annex land, a tract may be split in two, a new county may be created, etc.). The tables include data for a particular geographic unit only at times when the unit’s name or code was in use, resulting in truncated time series for some areas.

There are missing values in cases where a tract number exists in some years and not in others. And the 111,000+ tract numbers are the total that have ever existed since the earliest year in the time series. (There should be around 73,000 tract numbers with valid data for 2010.)

NHGIS also has geographically standardized time series that provide data only for the ~73,000 2010 census tracts, including estimates for 1990 and 2000. But we don’t yet have poverty counts in those. If you’d like to generate 1990 and 2000 poverty data for 2010 tracts, you might consider using our geographic crosswalks.

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Thank you, Jonathan!

Hi Jonathan,

I have a follow-up question. In order to use the crosswalk to generate 1990 and 2000 poverty data for 2010 tracts, I have to obtain the block-level poverty data, is that right? However, it looks like poverty data is not available at census block level?


You’re correct that poverty data are not available at the census block level…

  • Blocks are the lowest level for which the Census Bureau tabulates full-count, short-form summary data, covering subjects such as age, sex, race, household size, and housing tenure.
  • Block group parts are the lowest level for which the Census Bureau tabulated sample-based, long-form summary data in 1990 and 2000, covering subjects such as income, employment, education, nativity, migration, and commuting.

Poverty data are based on income info, which is a long-form subject, so the smallest units with poverty data are “block group parts.” NHGIS also provides crosswalks for block group parts, and the instructions for using them are here.

Thanks, Jonathan! Am I right that if I use the poverty data at the block-group level and use the block-group cross-walk, I can generate 1990 and 2000 poverty data for 2010 tracts?

You’ll need data for block group parts, not block groups. Block group parts are smaller partitions of block groups. See the documentation I linked to for more info. But then yes, you can use that data to generate 1990 and 2000 poverty data for 2010 tracts!

Awesome. Thank you!