I can see couple of distinct COUNTYFIPS, whereas the rest of them are under '0' COUNTYFIPS for Minnesota.

#1

I can see couple of distinct COUNTYFIPS, whereas the rest of them are under ‘0’ COUNTYFIPS for Minnesota.

#2

Code and output, please??

#3

The code is as follows:

proc freq data=IPUMS.usa_00007;

tables YEAR COUNTYFIPS;

run;

#4

#5

Take note of the limited availability of counties in public use data, as described in the Description Tab. In particular, counties are unavailable in public use data from 1950 onwards. It is possible to recover some counties from lower-level geographic identifiers if: (1) the counties were coterminous with a single identifiable State Economic Area (SEA), county group, or PUMA. Or (2) if counties contained multiple identifiable SEAs, county groups, or PUMAs and none of which extended into other counties. This Excel spreadsheet provides a list of counties available in each year from 1950 onwards.