This R package includes contemporary state, county, and congressional district boundaries for the United States of America provided by the [U.S. Census Bureau], as well as historical boundaries from 1629 to 2000 for states and counties from the Newberry Library’s Atlas of Historical County Boundaries. This package provides a set of functions, one for each of the types of boundaries that are available. These functions have a consistent interface described below.
Types of data
There are three kinds of boundaries provided by this package, each with its own function:
- State:
us_states()
- Counties:
us_counties()
- Congressional districts:
us_congressional()
In addition, the us_boundaries() function provides a wrapper around all of those functions for backward compatibility. But in general you are better off using the more specific functions.
Historical vs contemporary boundaries
The map_date = argument controls whether the functions return historical or contemporary boundary information. Leaving the argument NULL will always return contemporary boundaries.
library(USAboundaries)
library(sp) # for plotting
states <- us_states()
plot(states)
Passing a date as a character vector (or any object coercible to a date object with as.Date()) will return the boundaries for that day.
states_1790 <- us_states("1790-07-04")
plot(states_1790)
Historical data is only available for states and counties. The function us_congressional() only offers contemporary boundaries.
Selecting certain states
For any function, pass a character vector of state names to the states = argument to return only those states or territories.
counties <- us_counties(states = c("South Carolina", "North Carolina"))
plot(counties)
Resolution
For certain functions, more or less detailed boundary information is available by passing an argument to the resolution = argument. To use the higher resolution files you will need the USAboundariesData package. If that package is not available, you will be prompted to install it from the rOpenSci package repository.