mapTransform.R

# Read GADM file.
map <- readRDS( file = "USA_adm1.rds" )

# Create Data Frame from spatial object.
map <- fortify( map, region = "NAME_1")

# Create new state column without any special characters.
map$state <- stringi::stri_trans_general( str = map$id
                                        , id = "Latin-ASCII"
                                        )

# Remove Alaska and Hawaii
map <- map[ ! map$state %in% c( "Alaska", "Hawaii" ), ]