TIGER/Line and cartographic boundary files
In addition to its TIGER/Line shapefiles, the US Census Bureau releases cartographic boundary shapefiles for enumeration units. TIGER/Line shapefiles correspond to legal boundaries of units, which can include water area and in turn, may not be preferable for thematic mapping. The Census Bureau's cartographic boundary shapefiles are clipped to the US shoreline and are generalized, which can make them superior for mapping projects. In this exercise, you'll compare the TIGER/Line and cartographic boundary representations of the US state of Michigan.
This exercise is part of the course
Analyzing US Census Data in R
Exercise instructions
- Get a dataset of county boundaries for Michigan using default arguments.
- Get an equivalent counties dataset for Michigan, but set
cb = TRUEto request the cartographic boundary shapefile. - Plot both datasets, using
add = TRUEfor the second plotting call to create an overlay on the plot.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Get a counties dataset for Michigan
mi_tiger <- ___("MI")
# Get the equivalent cartographic boundary shapefile
mi_cb <- ___("MI", ___ = TRUE)
# Overlay the two on a plot to make a comparison
___(mi_tiger)
___(mi_cb, ___ = TRUE, border = "red")