# CITY codes vs FIPS codes

**URL:** <https://forum.ipums.org/t/city-codes-vs-fips-codes/7169>\
**Category:** USA\
**Created:** [September 3, 2026, 5:10pm UTC](https://forum.ipums.org/t/city-codes-vs-fips-codes/7169 "2026-09-03T17:10:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Robert\_Gebeloff](https://avatars.discourse-cdn.com/v4/letter/r/90db22/32.png) [@Robert\_Gebeloff](https://forum.ipums.org/u/Robert_Gebeloff)\
**Post date:** [September 3, 2026, 5:10pm UTC](https://forum.ipums.org/t/city-codes-vs-fips-codes/7169/1 "2026-09-03T17:10:54Z")

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This topic has come up [before](https://forum.ipums.org/t/is-there-a-way-to-link-place-fips-codes-to-the-variable-city-in-ipums-usa/1086), and there is a guide for how to link modern sample city codes to published FIPS codes, but this generally includes only the largest cities.

However, with the historical 100-percent data, there are many more identifiable cities. In 1940, for example, there are more than 900 City codes including many small and mid-sized cities not included in any of the IPUMS mapping files that I could find.

Has anyone ever mapped all of the CITY codes to modern Census FIPS?

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**Author:** ![Ivan\_Strahof](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.ipums.org/ivan_strahof/32/626_2.png) [@Ivan\_Strahof](https://forum.ipums.org/u/Ivan_Strahof)\
**Post date:** [September 17, 2026, 3:43pm UTC](https://forum.ipums.org/t/city-codes-vs-fips-codes/7169/2 "2026-09-17T15:43:23Z")

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The IPUMS data team is currently working on re-releasing PLACENHG which will map 1940 city codes (in the 1940 full count data) to modern Census FIPS codes. Specifically, PLACENHG will combine a state FIPS code with a place FIPS to form a nationally unique ID. Cities in 1940 without a modern FIPS will receive a pseudo FIPS code instead. This variable will be part of a forthcoming release on IPUMS USA. Once it is available, [the revision history](https://usa.ipums.org/usa-action/revisions) will be updated to reflect this change. If you require the data urgently, you may email our user support team directly at [ipums@umn.edu](mailto:ipums@umn.edu) and I will share the preliminary crosswalk between PLACENHG and CITY codes.

While PLACENHG will only be available in the 1940 full count, it will be possible to use a data extract to create a crosswalk between PLACENHG and the harmonized variable CITY. Such a crosswalk can then be used to assign PLACENHG codes to cities in other samples as long as the corresponding CITY is identified in the 1940 data. For reference, a bit fewer than 5% of cities identified in 1950 do not have a 1940 code and a bit more than 5% of cities identified in 1930 do not have a corresponding 1940 code.