devtools::install_github("jsta/glwdr")

library(glwdr)

glwd_get(level = 1)

dt <- glwd_load(level = 1)

library(maps)
library(sp)

dt <- dt[dt$COUNTRY == "United States" &
         dt$LAT_DEG < 56 &
         dt$AREA_SKM < 30000,] 
 
map("state")
plot(dt, add = TRUE, col = "blue")
axis(1); axis(2)

glwd_get(level = 2)

dt <- glwd_load(level = 2)

library(ggplot2)
library(raster)

states <- map_data("state")
states <- glwdr:::map_data_to_spdf(states)
projection(dt) <- projection(states)

map("state")
plot(dt[states,], add = TRUE, border = "blue")
axis(1); axis(2)

glwd_get(level = 3)

dt <- glwd_load(level = 3)

map("world")
plot(dt, breaks = 1:12, col = viridis::viridis(12), add = TRUE)
axis(1); axis(2)