These contain an abbreviated version of the "master records" for the Correlates of War direct contiguity data. Data contain a few cosmetic changes to assist with some functions downstream from it.
Format
A data frame with 1,874 observations on the following 5 variables.
ccode1a numeric vector for the Correlates of War state code for the first state
ccode2a numeric vector for the Correlates of War state code for the second state
conttypea numeric vector for the contiguity relationship
stdatea date communicating the start of the contiguity relationship
enddatea date communicating the end of the contiguity relationship
Details
The "master record" provided by the Correlates of War is "non-directed." I make these data "directed" for convenience.
For clarity, the contiguity codes range from 1 to 5. 1 = direct land
contiguity. 2 = separated by 12 miles of water or fewer (a la Stannis
Baratheon). 3 = separated by 24 miles of water or fewer (but more than 12
miles). 4 = separated by 150 miles of water or fewer (but more than 24 miles).
5 = separated by 400 miles of water or fewer (but more than 150 miles). Cases
of separation by more than 400 miles of water are here as 0. The documentation
for add_contiguity() belabors why you should not consider the contiguity
variable as ordinal.
stdate and enddate are simple date formats of the original begin and
end columns in the raw data. Correlates of War communicates contiguity
periods in a basic year-month format (YYYYMM). It's just easier to process
an actual date, provided you're careful and know that the day I communicate
in these columns means absolutely nothing.
The master record contains no entry for a non-continuous relationship, leaving
the user to figure that out for themselves. The data I provide here includes
information for non-contiguous relationships for all states that had, at least
at one point, a contiguous relationship. For example, there is just the one
entry a contiguous USA-Russia relationship (from Jan. 1959 to the end of the
data), but I also provide manual clarification of a non-continuous relationship
before that. You can check the data-raw directory for how I do this. This
is necessary for a case like Myanmar-Philippines, in which a contiguity
relationship enters the data in 1963 (but only for September of that year).
It would be important to note that the data say there was no contiguity
relationship in that dyad at the start of the year.
Be mindful that the data are fundamentally year-month. Sometimes the end date for one contiguity relationship overlaps with the start date for another contiguity relationship. Sometimes it doesn't. Since no day information is available in the data, the contiguity entries I impute for non-contiguous relationships cannot know whether, for example, the contiguity relationship that starts in Jan. 1959 started on the first of the month or sometime in the middle of the month.