Democrats won all five DuPage County Board seats at stake on Nov. 3, giving the party a 17-1 supermajority effective Dec. 1, according to unofficial results.

The margin is a mirror image of a decade ago. In 2016, Republicans held a 17-1 advantage on the board, with Liz Chaplin as the lone Democrat, Shaw Local reported. If results hold, Cindy Cronin Cahill will be its only Republican.

Two Glen Ellyn residents claimed seats. Paula McGowen, a Milton Township trustee, defeated incumbent Republican Grant Eckhoff with 33,821 votes to 21,987, according to the Daily Herald. Incumbent Democrat Mary FitzGerald Ozog, first elected in 2018, won her two-year term with 35,781 votes to Republican Isobel Michaud's 20,133.

In Lombard, attorney Mary Rada Walters won a two-year county board term with 38,228 votes to Republican Theresa McClear's 23,151, the Daily Herald reported. Walters said during the campaign she would advocate for more affordable housing.

The biggest upset came in District 6. Jesse Gutierrez, a West Chicago Democrat and political newcomer, ousted Jim Zay, the board's longest-serving member and a Carol Stream Republican, by a margin of 29,561 to 21,416.

Zay blamed national politics for the losses. "It does wear on Republican candidates when (Democrats) have negative ads comparing them to Trump," Zay said, according to the Daily Herald's analysis of the suburban results.

Three veteran GOP board members lost their seats. Zay, Brian Krajewski and Eckhoff had a combined 66 years on the board, Shaw Local's Cathy Janek reported. A fourth Republican, Kari Galassi, also lost after a single term.

Melissa Mouritsen, a political science professor at College of DuPage, said the scale of the shift caught even her off guard.

"I've been writing about the blue wave in DuPage since 2018, and even I didn't see such an obliteration," Mouritsen said.

She attributed the results to more than opposition to President Donald Trump. "I would reject any analysis that says this is only a rebuke of Trump," Mouritsen said. "That is an important part for sure, but this has been in motion for some time." She said the outcome combined 15 to 20 years of organizing with a long-term demographic shift and the national political environment.

The sweep extended beyond the county board. Democratic candidates won every contested race in DuPage County for the second consecutive year, Shaw Local reported. Democrats reelected County Board Chairwoman Deb Conroy, flipped the treasurer's office and regional superintendent of schools, held the clerk's office, and elected a sheriff. They also flipped state House Districts 47 and 48 and Senate District 24.

Democrats first took control of the board in 2020 when they secured 11 of 18 seats. Six years later, the previous 12-6 majority has ballooned to 17-1.

All results remain unofficial until the canvass.