Article on the researchDo your research and post your finding. Like to compare notes. There might be more info available than what I read

Pre-election polls in 2020 had the largest errors in 40 years
Public opinion polls ahead of the 2020 election were the most inaccurate in a generation, according to Josh Clinton, Abby and Jon Winkelried Chair and professor of political science, who recently served as chair of a special task force convened by the American Association for Public Opinion...

Link to the report: https://aapor.org/wp-content/upload...e-on-2020-Pre-Election-Polling_Report-FNL.pdf
Executive summary here: https://aapor.org/wp-content/upload...20-Pre-Election-Polling_Executive-Summary.pdf
- The polling error was much more likely to favor Biden over Trump. Among polls conducted in the last two weeks before the election, the average signed error on the vote margin was too favorable for Biden by 3.9 percentage points in the national polls and by 4.3 percentage points in statewide presidential polls.
- The polling error for the presidential election was stable throughout the campaign. The average error matched closely for polls conducted in the last two weeks, in the final week, and even in the final three days. The challenges polls faced in 2020 did not diminish as Election Day approached.
And here is 538's polling aggregate through 2020 from end of February through Election Day.
Biden consistently ahead the whole time.
