# Geographical Variables Held Constant Over Time

**URL:** <https://forum.ipums.org/t/geographical-variables-held-constant-over-time/3270>\
**Category:** USA\
**Created:** [December 3, 2019, 2:17am UTC](https://forum.ipums.org/t/geographical-variables-held-constant-over-time/3270 "2019-12-03T02:17:13Z")\
**Posts on this page:** 3\
**Page:** 1

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**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:** [December 3, 2019, 2:17am UTC](https://forum.ipums.org/t/geographical-variables-held-constant-over-time/3270/1 "2019-12-03T02:17:13Z")

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Do you know of any geographical variables for cities that are good for holding constant an area over time? Some variables, such as MDSTATUS and METDIST seem to do so, but they only go as far forward as 1940. METAREA seems good, though boundaries change over time. MET2013 would be good, but it does not go further back than 2000. Would there be any geographical variables whose borders would remain the same between 1970-2010 (or somewhere in that range)? If not, are there resources beyond that might help me? Thank you.

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**Author:** ![JeffBloem](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.ipums.org/jeffbloem/32/40_2.png) [@JeffBloem](https://forum.ipums.org/u/JeffBloem)\
**Post date:** [December 4, 2019, 6:16pm UTC](https://forum.ipums.org/t/geographical-variables-held-constant-over-time/3270/2 "2019-12-04T18:16:02Z")

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Analyzing consistent geographic boundaries over time is a persistent challenge with US census data. You’ve described many of the limitations above. Your best bet might be [CONSPUMA](https://usa.ipums.org/usa-action/variables/CONSPUMA#description_section). This is an IPUMS-derived variable that identifies consistent PUMA boundaries back through 1980. There are some limitations with the CONSPUMA variable, so you’ll want to read through the documentation on [this page](https://usa.ipums.org/usa/volii/conspuma.shtml) and [this page](https://usa.ipums.org/usa-action/variables/CONSPUMA#comparability_section). Additionally, the [time series variables](https://www.nhgis.org/documentation/time-series) available via IPUMS NHGIS may be of use to you.

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**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:** [December 5, 2019, 6:18pm UTC](https://forum.ipums.org/t/geographical-variables-held-constant-over-time/3270/3 "2019-12-05T18:18:01Z")

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Thank you very much.

Best,

Alex Mozell