NCSH County Codes to FIPS

nchs_fips.csv

This is essentially the CSV file from NBER listed here but with the separate State and County NCHS codes merged into a single 5 digit code consistent with the natality data files on NBER. (The county code needs padding to be a 3 digit with leading 0).

This was done in Duckdb with code like this:

CREATE TABLE 
nchs_map as SELECT CAST (CAST(nchs_state as varchar) || printf('%03d',nchs_county) as integer) as nchs_code ,fipsco,countyname,statename  
FROM 
countymap;

For the natality data from before 1980, the only county identifier is the NCHS code.

To join on this you have to cast cntyres or any other county code in the natality data as an integer, because I believe unknown counties show up as 59ZZZ for some years in the birth data files. So the missing leading zero in the files works fine.