Making another choropleth with an additional layer

Choropleth 2

townborders <- readOGR(dsn="shapes", layer="ctgeo")
townborders_only <- townborders
townborders<- fortify(townborders, region="NAME10")

# Subset the town borders to just Hamden since that's the department we're looking at
town_borders <- subset(townborders, id=="Hamden")

tm_ct <- ggplot() +
  geom_polygon(data = total_map, aes(x=long, y=lat, group=group, fill=total), color = "black", size=0.2) +
  geom_polygon(data = town_borders, aes(x=long, y=lat, group=group, fill=total), color = "black", fill=NA, size=0.5) +
  coord_map() +
  scale_fill_distiller(type="seq", trans="reverse", palette = "Reds", breaks=pretty_breaks(n=10)) +
  theme_nothing(legend=TRUE) +
  labs(title="Where Hamden police conduct traffic stops", fill="")
print(tm_ct)