The principal purpose of this shiny app is to demonstrate spatial subsetting in R through the sf package. It accompanies a series of lessons on GIS in R, including manipulation and mapping, found on the Social Cops blog. Steps for preparation of the data in this app using the tidyverse and sf packages are detailed there.
The median household income data comes from the 2012-2016 5-year American Community Survey (ACS) and was downloaded via the tidycensus package. The census tract shapefiles were downloaded with the support of the tigris package.
The code for this app can be found on GitHub.
Other data projects by the author can be found at https://sean.rbind.io