Aligning ggmap and geom_sf maps

Question

I am having problems aligning two maps. They appear to have the same crs but still look off a bit. Notice the California-Nevada border and the California coast. Below is the code I am using:

library(ggmap)
 library(sf)
 library(USAboundaries)

state_names <- c("california") 
CA_counties <- us_counties(resolution="high",states=state_names)
CAbox <- c(bottom = 32.213, top = 42.163 , right = -113.95, left = -124.585)
camap2 <- get_stamenmap(bbox = CAbox, zoom = 6, maptype = "terrain")
ggmap(camap2)

ggmap(camap2) + geom_sf(data=CA_counties,color='red',inherit.aes = FALSE,alpha=0.2) +
 theme_void()

Could someone guide me in the right direction? Thanks