Immediately after the polls closed at 7:00 pm Central Time, the Associated Press declared former vice president Joe Biden the winner of the Illinois primary.

Together with his victories on the same day in Florida and Arizona, Biden greatly expanded the gap in delegates between him and Sanders.

In the open primary, candidates had to meet a threshold of 15 percent at the congressional district or statewide level in order to be considered viable.

The 155 pledged delegates to the 2020 Democratic National Convention were allocated proportionally on the basis of the results of the primary.

[6] National convention district level delegates were listed on the ballot and chosen during the primary.