library(rtweet)
library(dplyr)

files <- list.files()
files <- files[grep(".json", files)]

getPoints <- function(file){
  parse_stream(file) %>%
    lat_lng("bbox_coords") %>% # keep bounding box coords
    filter(is_retweet == FALSE & !is.na(lat)) %>% # keep posts and point lat/longs
    select(status_id, created_at, screen_name, text, is_retweet, lat, lng) # whatever columns to select
}

df <- purrr::map_df(files, getPoints)

## plot state boundaries
par(mar = c(0, 0, 0, 0))
maps::map("state", lwd = .25)

## plot lat and lng points onto state map
with(df, points(lng, lat, pch = 20, cex = .75, col = rgb(0, .3, .7, .75)))