Census Tract with 0 or missing population

NHGIS
1

Hello,

I am using NHGIS data for decennial census 1990-2000, and ACS 2008-2012 and 2018-2022. I’ve downloaded census-tract level population data (using the NHGIS time series based on nominal census tracts). I have a couple of questions/clarifications:

  1. There are a lot of missing values for specific census tracts in specific years - I am interpreting this as census tracts that were either newly created, or that disappeared. For instance, if a new census tract was created in 2020, that census tract will have missing population data for the previous years. Is this right? Am I missing something?

  2. There are Census tracts with 0 population in certain years. How should I interpret these? I’ve manually checked a few of those - they seem to be located in rural areas, but ti is still surprising that the population is 0, right? Do you know what might be the reason?

Thanks!
Giulia

2
  1. Yes, your understanding is correct about the cases of missing values for census tracts in nominally integrated time series tables. For more information, see the section about nominally integrated tables in our time series table documentation.
  2. Census tracts are generally designed to have about 4,000 people in them, mostly ranging between 2,500 and 8,000, but it’s also not uncommon for tracts to encompass certain special areas with no population or very small populations. In my experience, these areas are usually over water, a large park (e.g., Central Park in Manhattan), an airport, or some other unique land use. As such, I wouldn’t expect you’d find them to be more common in rural areas, though there are some there, too. Also, these tracts’ numbers are typically 6 digits long (including decimal places) and begin with 9 (e.g. 9901.00, or 990100 without the decimal point). If you’re finding a different pattern of zero counts, please provide some examples, and we can investigate further.
3

Thank you!!