The data comes from the American Community Survey (ACS). 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_congressional_district_demographics(year = 2018, survey = "acs5")
The year the survey was published
The survey. Either "acs5" or "acs1"