map_US_MeXwithstates_sites

ryp<-read.table(file.choose(), sep=",", header=TRUE )
cryp$pop

library(rgeos)
library(sf)
library(rgdal)
library(maps)
na_sf <- st_as_sf(map("world", regions=c("usa", "canada", "mexico"), plot = FALSE, fill = TRUE))
conus_sf <- st_as_sf(map("state", plot = FALSE, fill = TRUE))
na2_sf <- rbind(na_sf, conus_sf)

P<-ggplot(data = na2_sf ) +
  geom_sf(fill = "cornsilk") +
  geom_jitter(data = cryp, aes(x = Long, y = Lat,color = pop, size =1.0,),position = position_jitter(width = 0.2, height = 0.1)) +
   # annotate(geom = "text", x = -168, y = 58, label = "Bering Sea",  # edit to add in text to map 
     #      fontface = "italic", color = "grey22", size = 5) +
  coord_sf(xlim = c(-110.15, -70.01), ylim = c(18, 45.2), expand = FALSE)+ # coords of plot
  xlab("Longitude") + 
  ylab("Latitude")
#ggtitle("Map of XX sites")

P + theme(panel.grid.major = element_line(colour = gray(0.5), linetype = "dashed", 
                                          size = 0.5), panel.background = element_rect(fill = "aliceblue"), 
          panel.border = element_rect(fill = NA)) 

#Manually color points
P + scale_color_manual(values=c("green", "red", "purple", "blue","Orange","grey"))
P
dev.off()