**Democrat Sarah Trone Garriott defeated Republican incumbent Zach Nunn in Iowa’s 3rd congressional district on November 3, 2026, with unofficial results showing her at approximately 53–54% of the vote to Nunn’s 46%.** This produced a margin in the 6–9 point range that aligns with the leading Polymarket outcome priced at 87.5%. Race ratings from Cook, Sabato, and Inside Elections had shifted to Lean or Tilt Democratic in October amid Garriott’s fundraising edge and a national midterm environment that favored Democratic gains in competitive House seats. The district, which includes Des Moines and growing suburbs, had been held by Republicans since 2022 after a narrow 2024 presidential margin; early and absentee vote patterns, combined with final precinct reporting, locked in the observed spread and reduced uncertainty around narrower or wider outcomes. Trader consensus priced the 6–9% band highest because vote counts confirmed that range while other intervals received far lower implied probability.