# Visualising the contiguous United States

This package provides three different shapefiles for the United States of America, comprising; state boundaries, congressional districts and counties. These are stored as `sf` objects, if you're not familiar with the excellent `sf` approach to geometric features it's highly recommended you glace at the documentation - https://r-spatial.github.io/sf//index.html

The `sf` objects contain a column called `contiguous.united.states` which allows us to restrict ourselves to only the contiguous US. This is how we might visualise the congressional districts of the contiguous US with leaflet:

    library("statesRcontiguous")
    library("tidyverse")
    library("leaflet")
    shp_contiguous_us_congressional_districts <- shp_all_us_congressional_districts %>%
      filter(contiguous.united.states)
    shp_contiguous_us_congressional_districts %>%
      leaflet() %>%
      addTiles() %>%
      addPolygons(weight = 1)

# Where are the shapefiles from?

All of the shapefiles in this package are from the US Census website - https://www.census.gov/geo/maps-data/data/tiger-cart-boundary.html. This package will continuously be updated with the most recent shapefiles, historical shapefiles will not be available in this package. If that's what you want, please do use the `tigris` package - https://github.com/walkerke/tigris.

The explicit urls for the shapefiles are available here:

    knitr::kable(shapefile_details)

description | year | url
--- | --- | ---
Details about congressional districts | 2016 | https://www2.census.gov/geo/tiger/TIGER2016/CD/tl_2016_us_cd115.zip
Details about counties | 2016 | https://www2.census.gov/geo/tiger/TIGER2016/COUNTY/tl_2016_us_county.zip
Details about states | 2016 | https://www2.census.gov/geo/tiger/TIGER2016/STATE/tl_2016_us_state.zip
Shapefile for congressional districts | 2016 | http://www2.census.gov/geo/tiger/GENZ2016/shp/cb_2016_us_cd115_20m.zip
Shapefile for counties | 2016 | http://www2.census.gov/geo/tiger/GENZ2016/shp/cb_2016_us_county_20m.zip
Shapefile for states | 2016 | http://www2.census.gov/geo/tiger/GENZ2016/shp/cb_2016_us_state_20m.zip