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我之前有一篇文章是关于使用GADM中的形状文件绘制美国地图，同时删除五大湖地区的颜色映射。根据@Majid 的建议解决了该问题。

现在，我进一步想要更厚的州边界和更薄的县边界。我首先绘制县级分区统计图，然后添加额外的未填充的州/国家级边界：

library(sf)
library(tidyverse)
library(RColorBrewer) #for some nice color palettes

# US map downloaded from https://gadm.org/download_country_v3.html

# National border
us0 <- st_read("<Path>\\gadm36_USA_0.shp")
# State border
us1 <- st_read("<Path>\\gadm36_USA_1.shp")
# County border
us2 <- st_read("<Path>\\gadm36_USA_2.shp")

# Remove the Great Lakes
# retrieving the name of lakes and excluding them from the sf 
all.names = us2$NAME_2
patterns = c("Lake", "lake")

lakes.name <- unique(grep(paste(patterns, collapse="|"), 
                     all.names, 
                     value=TRUE, ignore.case = TRUE))

# Pick the Great Lakes
lakes.name <- lakes.name[c(4, 5, …