# Geography Held Constant **URL:** \ **Category:** USA\ **Created:** [November 24, 2019, 10:53pm UTC](https://forum.ipums.org/t/geography-held-constant/3265 "2019-11-24T22:53:29Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Alexander\_Mozell](https://avatars.discourse-cdn.com/v4/letter/a/e79b87/32.png) [@Alexander\_Mozell](https://forum.ipums.org/u/Alexander_Mozell)\ **Post date:** [November 24, 2019, 10:53pm UTC](https://forum.ipums.org/t/geography-held-constant/3265/1 "2019-11-24T22:53:29Z")
Which geographical variable should I use to hold urban geographical regions constant across decades? Is there anything I should know about implementing this? Thank you. ---
**Author:** ![JonathanSchroeder](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.ipums.org/jonathanschroeder/32/70_2.png) [@JonathanSchroeder](https://forum.ipums.org/u/JonathanSchroeder)\ **Post date:** [November 25, 2019, 4:25pm UTC](https://forum.ipums.org/t/geography-held-constant/3265/2 "2019-11-25T16:25:36Z")
The most relevant IPUMS USA variables are [METAREA](https://usa.ipums.org/usa-action/variables/METAREA) and [MET2013](https://usa.ipums.org/usa-action/variables/MET2013). METAREA is [available for 1850 through 2011](https://usa.ipums.org/usa-action/variables/METAREA#availability_section) samples, but it does not hold geographic regions constant. It uses contemporary delineations of metro areas, which is appropriate insofar as changes in metro area boundaries reflect “real” growth in metro regions. MET2013 uses constant metro area delineations (those of 2013), but is [available only for samples back to 2000](https://usa.ipums.org/usa-action/variables/MET2013#availability_section). See the [METAREA Comparability page](https://usa.ipums.org/usa-action/variables/METAREA#comparability_section) for info on how its basis changes over time. See the [MET2013 Comparability page](https://usa.ipums.org/usa-action/variables/MET2013#comparability_section) for info on how MET2013 differs from METAREA. ---
**Author:** ![Alexander\_Mozell](https://avatars.discourse-cdn.com/v4/letter/a/e79b87/32.png) [@Alexander\_Mozell](https://forum.ipums.org/u/Alexander_Mozell)\ **Post date:** [November 25, 2019, 9:27pm UTC](https://forum.ipums.org/t/geography-held-constant/3265/3 "2019-11-25T21:27:00Z")
Thank you very much! ---
**Author:** ![Alexander\_Mozell](https://avatars.discourse-cdn.com/v4/letter/a/e79b87/32.png) [@Alexander\_Mozell](https://forum.ipums.org/u/Alexander_Mozell)\ **Post date:** [November 25, 2019, 9:37pm UTC](https://forum.ipums.org/t/geography-held-constant/3265/4 "2019-11-25T21:37:31Z")
I have a quick follow-up. Does METAREA hold the individual units of geography constant? This is really my main concern. Census Tracts (and other delineations) change over time and do not work for my research. Would METAREA work for this purpose and, if not, where might I find a variable type that would? This, I believe, is one thing that IPUMS excels at. I’m sorry if I was not clearer in my original question. ---
**Author:** ![JonathanSchroeder](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.ipums.org/jonathanschroeder/32/70_2.png) [@JonathanSchroeder](https://forum.ipums.org/u/JonathanSchroeder)\ **Post date:** [November 25, 2019, 10:46pm UTC](https://forum.ipums.org/t/geography-held-constant/3265/5 "2019-11-25T22:46:24Z")
And I’m sorry I didn’t state this more clearly in my original response: IPUMS USA has no variable that identifies geographically static urban regions across all samples, and I don’t know of another source of one. (I appreciate your faith in IPUMS’s integration prowess, but I’m afraid there are some integration challenges that even IPUMS has not yet conquered!) Two other variables that might be useful for you: [CONSPUMA](https://usa.ipums.org/usa-action/variables/CONSPUMA) identifies “consistent PUMAs” for all samples from 1980-2011, and [CPUMA0010](https://usa.ipums.org/usa-action/variables/CPUMA0010) identifies consistent PUMAs for 2000 through the most recent ACS sample. I know some research applications have constructed long time series of metro area data. If you can used pre-defined census summary tables (rather than microdata) for your research application, you could construct such time series by obtaining county-level data from [IPUMS NHGIS](https://www.nhgis.org/) and aggregating it up to metro areas, using the Census Bureau’s [delineation files](https://www.census.gov/programs-surveys/metro-micro/about/delineation-files.html) to identify associations between counties and metro areas. You’d still have to do some extra work to deal with some [county definition changes](https://www.census.gov/programs-surveys/geography/technical-documentation/county-changes.2010.html) across time. ---
**Author:** ![Alexander\_Mozell](https://avatars.discourse-cdn.com/v4/letter/a/e79b87/32.png) [@Alexander\_Mozell](https://forum.ipums.org/u/Alexander_Mozell)\ **Post date:** [November 25, 2019, 11:20pm UTC](https://forum.ipums.org/t/geography-held-constant/3265/6 "2019-11-25T23:20:37Z")
Thank you very much, I really appreciate all your help. Best, Aleex