Let's start with what I think is the most important error of the 2020 election: the national polling. The national polling average in 2016 overestimated Hillary Clinton's margin by less than 2 points, so the polling this year was worse. Historically, polling errors were greatest from 1936 to 1952, when scientific polling was first getting started. This is especially true on the state level where the state polling left much to be desired in 2020, as it did four years ago. Perhaps the best way to think about the state polling (and polling at large) is to borrow a phrase from the Trump era: take it seriously, but not too literally.

Source: CNN December 26, 2020 13:18 UTC