How many 2024 congressional races were decided by under 0.5% and which states were they in?
Executive summary
Ballotpedia’s margin analysis identifies races decided by razor-thin margins in 2024: the closest U.S. House race was California’s 13th CD (Adam Gray over John Duarte by 0.09 points, 187 votes) and the closest U.S. Senate race was Michigan (Elissa Slotkin over Mike Rogers by 0.34 points) [1]. Ballotpedia also counts broader tiers of close contests—80 congressional races were decided by 10 points or fewer and 43 by five points or fewer—but available sources do not provide a single, published list that counts exactly how many congressional races were decided by under 0.5% across both chambers [2] [1].
1. What the core sources say about sub‑half‑percent margins
Ballotpedia’s congressional margin analysis highlights individual sub‑0.5% outcomes: California’s 13th Congressional District was decided by 0.09 points (187 votes) and the narrowest Senate result was Michigan at 0.34 points [1]. Ballotpedia separately catalogs races decided by 10 points or fewer (80 races total: 69 House, 11 Senate) and by five points or fewer (43 races: 37 House, six Senate) but does not publish, in the excerpts provided, a tabulation specifically counting all congressional races under 0.5% [2] [1]. Available sources do not mention a consolidated count of all congressional (House + Senate) contests decided by under 0.5% in 2024.
2. Known sub‑0.5% congressional examples and their states
From the materials given, the clearest sub‑0.5% congressional examples are: California’s 13th Congressional District (House, 0.09 points) and Michigan’s U.S. Senate race (Senate, 0.34 points) [1]. Ballotpedia also states that “the narrowest elections in both chambers were decided by margins under one percentage point,” confirming multiple single‑digit narrow outcomes but not enumerating every sub‑0.5% case in the supplied excerpts [1]. The Ballotpedia legislative margins page lists many state legislative races under 0.5% (47 races) but that is for state legislatures, not Congress [3].
3. Why a single, definitive count is elusive in provided reporting
Ballotpedia provides comprehensive tables and rolling updates; the excerpts show they track margins and list closest races, but the snippets do not include a ready total of all congressional races under 0.5% [1] [2]. Wikipedia and other summaries emphasize numbers of races under wider thresholds (5% or 10%) and overall House seat counts, not a sub‑0.5% tally [4] [2]. Therefore, any exact national count of sub‑0.5% congressional contests is not in the available excerpts—additional Ballotpedia tables or a dataset would be needed to produce a precise list and per‑state breakdown [1] [2].
4. Two competing perspectives from the sources
One perspective (Ballotpedia) frames 2024 as more competitive than 2022 on average and highlights extremely narrow races with concrete examples (CA‑13, MI Senate) to show how control margins hinge on tiny vote totals [1]. Another perspective (Wikipedia/Sabato’s Crystal Ball in the snippets) emphasizes overall outcomes—Republicans retaining a narrow House majority (220–215)—and broader competitiveness metrics like the number of races decided within 10% or 5% rather than the sub‑0.5% floor [4] [2] [5]. Both views are consistent: the cycle had many close contests, but reporting priorities differ between granular margin tracking and high‑level seat tallies [1] [4] [2].
5. What this means politically and procedurally
Extremely narrow margins matter institutionally: a handful of votes (187 in CA‑13) can determine which party controls committees and the House floor agenda, and slim majorities (220–215) amplify the political weight of every contested seat [1] [6] [5]. Ballotpedia’s focus on margins underlines that numerous races were competitive enough to prompt recounts, legal challenges, or heightened post‑election scrutiny—though the provided excerpts do not catalog which contests had recounts or litigation [1] [2]. Available sources do not mention the complete list of sub‑0.5% races or which states beyond California and Michigan had such margins.
6. How to get the exact count and full state list
To produce a definitive, state‑by‑state list of all 2024 congressional races decided by less than 0.5%, consult the full Ballotpedia margin tables referenced in their margin‑of‑victory analysis pages or exported datasets behind their congressional results pages (Ballotpedia links cited above)—the excerpts demonstrate they track this level of granularity, but the complete table was not included in the supplied snippets [1] [2]. If you want, I can fetch and parse those Ballotpedia tables (or equivalent official state canvass reports) and produce a complete count and per‑state list.