County FIPS codes seem wrong?

Hi there - hopefully someone can help me!

I am trying to filter data down to the county level in Maryland using county FIPS codes. I am under the impression that they are 5-digit codes that begin with 24 (the code for Maryland) and end with the three-digit county FIPS code. Ex: 24031 for Montgomery County.

However, as I am looking through the CPS dataset, I see county FIPS codes from numbers like 530 all the way up to 99990. Is there a data source someone can point me to that has county codes that match up to these? Or can someone explain why the county FIPS codes look so different than the ones I’m used to seeing?

FYI, I pulled county data from CPS in May and all the codes are matching up so I’m not sure what’s going on.

Thanks in advance!

I just downloaded an IPUMS CPS extract and checked the SDA system, and in both cases the codes for COUNTY (apart from 0) range from 1003 to 55139. As you said, the first two digits indicate the two-digit state FIPS code. Four-digit codes occur when the state FIPS code is less than 10.

I wonder if you are accidentally looking at the codes for COUNTYFIP at IPUMS USA? For that project, the state codes are not concatenated to the county codes, so this variable is only 3 digits.

Hi Matthew,

Thanks for responding so quickly! I downloaded the data again just to make sure I did it correctly, using the COUNTY variable from CPS. When I upload it into R and look at the unique county values, it goes from 0 to 99990 in increments of 10. So: 0, 10, 20… 2460, 2470… 99980, 99990.

Is there something that I’m overlooking or may have done incorrectly?

I was able to open your extract #2 in R and saw the same patterns in COUNTY as I previously described. How are you loading the data into R? Did you use the command file (which makes use of the command ipumsr) and the DDI metadata available from the IPUMS data downloads page? Please follow up with an email to for more support on this.