How did geography shape the results of the 2020 presidential election?

Biden’s strongest support in Illinois came from the heavily populated northeastern part of the state, especially the Chicago area and Cook County. Those counties’ large populations gave him enough votes to overcome Trump’s support in many downstate counties. So counties in northeastern Illinois helped win the state for Biden; the southern, western, and central regions did not do so for him.

AI-written and checked against the verified answer.