Numeric codes and names of 50 states and the District of Columbia, required to parse Keith Poole and Howard Rosenthal's collections of U.S. Congressional roll calls.
integer, numeric code for state used by the Inter-university Consortium for Political and Social Research
character, name of state or
NA, year of statehood
readKH converts the integer ICPSR codes
into strings, via a table lookup in this data frame. Another table
state.abb provides the 2-letter abbreviation
commonly used in identifying American legislators, e.g.,
KENNEDY, E (D-MA).
Various ICPSR codebooks. http://www.icpsr.umich.edu