Incumbent Liz Chaplin was victorious in the Democratic primary to represent District 2 on the DuPage County Board.
Chaplin, the lone Democrat on the board, received 48.94 percent of the vote in the three-way race, according to unofficial results from the DuPage County Election Commission.
The Downers Grove resident will be joined on the November ballot by Arlene Kendorski, also of Downers Grove, who garnered about 26.1 percent of the vote, according to unofficial results.
Claire Goldenberg of Lisle finished third, receiving about 25 percent of the vote, preliminary numbers show.
Chaplin and Kendorski will face Republican candidates Steve Nero and Peter DiCianni in the November general election.
Nero, a Westmont trustee, and DiCianni, a County Board member since 2012, ran unopposed in the GOP primary.
District 2 includes all or parts of Lombard, Villa Park, Elmhurst, Oak Brook, Oakbrook Terrace, Westmont, Downers Grove, Hinsdale, Clarendon Hills, Woodridge, Lisle and Naperville.