R/south_df.R

In aslez/aiR: Areal interpolation and geographic aggregation

#' Overlap between 1860 and 2000 counties.
#'
#' A dataset containing data on group overlap based on the intersection of
#' United States counties from 1860 and 2000.  The original geographic data
#' were drawn from the National Historical Geographic Information System
#' (NHGIS).  Intersections and areas were calculated using QGIS.
#'
#' @docType data
#' @name south_df
#' @usage data(south_df)
#' @format A data frame with 3826 rows and 3 variables:
#' \itemize{
#'   \item ID1860. NHGIS identifier (GISJOIN) for 1860.
#'   \item ID2000. NHGIS identifier (GISJOIN) for 2000.
#'   \item AREA.  Area of overlap measured in square miles.
#' }
#' @source \url{https://www.nhgis.org/}
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