The data comes from the American Community Survey (ACS). The geographic unit is Zip Code Tabulated Areas (ZCTAs). The variables are: total population, percent White not Hispanic, Percent Black or African American not Hispanic, percent Asian not Hispanic, percent Hispanic all races, per-capita income, median rent and median age.
get_zip_demographics(endyear = 2013, span = 5)
The end year for the survey
The span of the survey
The choroplethr guide to Census data: http://cran.r-project.org/web/packages/choroplethr/vignettes/e-mapping-us-census-data.html
A list of all ACS Surveys: http://factfinder.census.gov/faces/affhelp/jsf/pages/metadata.xhtml?lang=en&type=survey&id=survey.en.ACS_ACS