Geoffrey Skelley of FiveThirtyEight –
Going into the presidential election, we expected President Trump to have an advantage in the Electoral College because the key battleground states were more Republican-leaning than the country as a whole. And that, in fact, is exactly how things panned out: Trump and the Republicans enjoyed the largest Electoral College edge in more than 70 years.
We can see just how large this advantage was if we average the margins in the two “tipping-point” states of Pennsylvania and Wisconsin, or the states that delivered (or would have delivered) the decisive 270th electoral vote Biden and Trump needed to win, respectively. (Biden’s tipping-point state was Wisconsin, while Trump’s would have been Pennsylvania, provided he also won Georgia, Arizona and Wisconsin.1) Averaged together, their margin was about D+0.9 points, or roughly 3.5 points more Republican-leaning than the national popular vote margin. This is significant because, as you can see in the chart below, the last time a party had an advantage this large — or larger — in the Electoral College was in 1948, when the GOP’s edge was 3.8 points.
Radnor Reports: Information for decision-makers 