Why we can't easily compare Joe Biden's approval ratings with past presidents' numbers

Polarization has introduced hard upper and lower bounds to a president's performance, making longer historical comparisons irrelevant without proper context

Today is Biden’s 99th day in office. Tomorrow, on his 100th, I expect we will see a torrent of news articles comparing his approval rating to past presidents’ numbers.

Most of these articles risk making a big mistake.

Because political polarization has increased so much since the 20th century, we can no longer expect a president to receive a traditional…