Suppose I had voting data from the 2016 election at voting district level, and population data (from 2010 Census, say) at the block or tract level. I am hoping there are no blocks/tracts in two districts. So assume that all we have to do is amalgamate up with no boundary issues. The data are in shapefiles.
What's the easiest way to use R to compare the polygons representing blocks/tracts with voting districts and then just sum the population of all the blocks/tracts within a voting district to calculate the total population of that district?
EDIT: I have found that this is very easy in ArcGIS using the join functionality, so I will just use that.