subset_county_polygons

Source: R/subset_county_polygons.R

Returns county polygons from: Siczewicz, Peter. U.S. Historical Counties (Generalized .001 deg) on the basis of year of interest Dataset is subset on basis of area of interest

subset_county_polygons(year, area_column, areas)

Arguments

year

int, the year of interest to be mapped (defines historical basis for counties)
area_column

chr, defines which column to use to specify area
areas

chr, vector of codes indicating HUCs, counties, states, regions, aquifers, etc.

Value

hc_sub dataframe, a subset of county polygon data

Examples

areas <- "Delaware" # 3 counties present day
area_column <- "STATE_TERR"
year <- 2010
hc_sub <- subset_county_polygons(year, area_column, areas)
hc_sub$NAME
#> [1] "KENT"       "NEW CASTLE" "SUSSEX"    
areas <- "Maine" # 16 counties present day
area_column <- "STATE_TERR"
year <- 2010
hc_sub <- subset_county_polygons(year, area_column, areas)
hc_sub$NAME
#>  [1] "ANDROSCOGGIN" "AROOSTOOK"    "CUMBERLAND"   "FRANKLIN"     "HANCOCK"     
#>  [6] "KENNEBEC"     "KNOX"         "LINCOLN"      "OXFORD"       "PENOBSCOT"   
#> [11] "PISCATAQUIS"  "SAGADAHOC"    "SOMERSET"     "WALDO"        "WASHINGTON"  
#> [16] "YORK"        
year <- 1850 # Maine had 13 counties in 1850; Delaware 3
hc_sub <- subset_county_polygons(year, area_column, areas)
hc_sub$NAME
#>  [1] "AROOSTOOK"   "CUMBERLAND"  "FRANKLIN"    "HANCOCK"     "KENNEBEC"   
#>  [6] "LINCOLN"     "OXFORD"      "PENOBSCOT"   "PISCATAQUIS" "SOMERSET"   
#> [11] "WALDO"       "WASHINGTON"  "YORK"