我怎样才能在ggplot2中绘制CONUS地图？

So, I have a dataset that has data for not only CONUS but also the island areas and Alaska. Now, I want to plot only the data for CONUS. I know I can subset it easily. But is there any easier way to that? Maybe an option in ggplot I don't know?So, I have a dataset that has data for not only