I want to re-share a post from Mary Johnson Zoom Into the Population of Every US County and add to it a link to a resource guide from past presidential elections https://www.loc.gov/rr/program/bib/elections/index.html so that you can combine a lesson on the electoral college and population with past presidential elections that have seen mixed results within the popular and electoral college votes (1824, 1876, 1888, 2000, and 2016).
Within the presidential elections resource guide, you can select specific years and find wonderful primary resources to go along with your studies.
Happy trails!