These are the independent states in Gleditsch and Ward's data.
gw_states
A data frame with 216 observations on the following 5 variables.
gwcode
a numeric vector for the Gleditsch-Ward country code
stateabb
a character vector for state abbreviation
statename
a character vector for the state name
startdate
the start date in the data
enddate
the end date in the data
Data originally provided by Gleditsch with no column names. Column names were added before some light re-cleaning in order to generate these data.
Gleditsch, Kristian S. and Michael D. Ward. 1999. "A Revised List of Independent States since the Congress of Vienna" 25(4): 393--413.