MLP Linkage File Does Not Work Out of the Box When Linking to 1940


I am a “new” user of the MLP linkage infrastructure MLP Linked Data and using the free script that IPUMS provides for linking Decennials:

For linking 1920 to 1940, the script does not work on my Mac machine. On the line:

quietly joinby histid_year_b' using "path’/extract_2'_to_merge.dta", unmatched(both) _merge(link_year_a’_`year_b’)

I get the error:

variable histid_1940 not found

I haven’t seen much on Census linkages in the forum so I thought I would document this. The error appears to be in the creation of the linkage file:


which is in fact missing the hist_1940 variable.