library(maps)

map()   # state map of the USA
map('usa')      # national boundaries
map('county', 'new jersey')     # county map of New Jersey
#     map(region=c('new york','new jersey','penn'))   # map of three states
map(proj='bonne', param=45)     # Bonne equal-area projection of states
map('county', 'washington,san', names=T, plot=F)
# names of the San Juan islands in Washington state
#     map(xlim=range(ozone.xy$x), ylim=range(ozone.xy$y))
#     text(ozone.xy, ozone.median)
# plot the ozone data on a base map
map(interior=F); map(boundary=F, lty=2, add=T)
# national boundaries in one color, state in another