Iowa State Senate District 8

Next vote Tue, Nov 3, 2026 · Represented by Mark Costello Republican · Member list as of Oct 28

This seat has no race on the official 2026 list.

Last election: Mark Costello (Republican) won by 41.2 points, 2024

More about this seat

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Official results for Iowa

History (15 elections for this seat)

Votes for listed candidates: 35,574
Election day: November 5, 2024
District map: Older district map (2022 to 2024)

Iowa Senate District 8, 1972 to 2024, 2024, every candidate
Candidate	Party	Votes and share	Share
RepublicanMark CostelloWon	Republican	25,06970.5%	70.5%
DemocraticRyan Lee Roenfeld	Democratic	10,43229.3%	29.3%
Scattered write-ins	Write-in	730.2%	0.2%

Votes for listed candidates: 23,766
Election day: November 3, 2020
District map: Older district map (2012 to 2021)

Iowa Senate District 8, 1972 to 2024, 2020, every candidate
Candidate	Party	Votes and share	Share
RepublicanDan DawsonWon(incumbent)	Republican	12,39152.1%	52.1%
DemocraticSteve Gorman	Democratic	11,34447.7%	47.7%
Scattered write-ins	Write-in	310.1%	0.1%

Votes for listed candidates: 22,933
Election day: November 8, 2016
District map: Older district map (2012 to 2021)

Iowa Senate District 8, 1972 to 2024, 2016, every candidate
Candidate	Party	Votes and share	Share
RepublicanDan DawsonWon	Republican	12,37954.0%	54.0%
DemocraticMichael E. Gronstal(incumbent)	Democratic	10,51045.8%	45.8%
Scattered write-ins	Write-in	440.2%	0.2%

Votes for listed candidates: 22,863
Election day: November 6, 2012
District map: Older district map (2012 to 2021)

Iowa Senate District 8, 1972 to 2024, 2012, every candidate
Candidate	Party	Votes and share	Share
DemocraticMichael E. GronstalWon(incumbent)	Democratic	12,63255.3%	55.3%
RepublicanAl Ringgenberg	Republican	10,19844.6%	44.6%
Scattered write-ins	Write-in	330.1%	0.1%

Votes for listed candidates: 28,698
Election day: November 4, 2008
District map: Older district map (2002 to 2011)

Iowa Senate District 8, 1972 to 2024, 2008, every candidate
Candidate	Party	Votes and share	Share
DemocraticMary Jo WilhelmWon	Democratic	14,86251.8%	51.8%
RepublicanMark Zieman(incumbent)	Republican	13,83648.2%	48.2%

Votes for listed candidates: 28,275
Election day: November 2, 2004
District map: Older district map (2002 to 2011)

Iowa Senate District 8, 1972 to 2024, 2004, every candidate
Candidate	Party	Votes and share	Share
RepublicanMark ZiemanWon(incumbent)	Republican	15,68255.5%	55.5%
DemocraticJohn Beard	Democratic	12,59344.5%	44.5%

Iowa Senate District 8, 1972 to 2024, 2002, every candidate
Candidate	Party	Votes and share	Share
RepublicanMark ZiemanWon(incumbent)	Republican	11,52956.7%	56.7%
DemocraticLyle Otte	Democratic	8,81743.3%	43.3%

Votes for listed candidates: 24,531
Election day: November 7, 2000
District map: Older district map (1992 to 2001)

Iowa Senate District 8, 1972 to 2024, 2000, every candidate
Candidate	Party	Votes and share	Share
RepublicanE. Thurman GaskillWon	Republican	13,94356.8%	56.8%
DemocraticWilliam S. Farnham	Democratic	10,58843.2%	43.2%

Votes for listed candidates: 24,686
Election day: November 5, 1996
District map: Older district map (1992 to 2001)

Iowa Senate District 8, 1972 to 2024, 1996, every candidate
Candidate	Party	Votes and share	Share
RepublicanJames Edward BlackWon	Republican	13,15053.3%	53.3%
DemocraticBerl E. Priebe(incumbent)	Democratic	11,53646.7%	46.7%

Votes for listed candidates: 26,133
Election day: November 3, 1992
District map: Older district map (1992 to 2001)

Iowa Senate District 8, 1972 to 2024, 1992, every candidate
Candidate	Party	Votes and share	Share
DemocraticBerl E. PriebeWon(incumbent)	Democratic	13,22350.6%	50.6%
RepublicanLarry E. Miller	Republican	12,91049.4%	49.4%

Votes for listed candidates: 22,994
Election day: November 8, 1988
District map: Older district map (1982 to 1991)

Iowa Senate District 8, 1972 to 2024, 1988, every candidate
Candidate	Party	Votes and share	Share
DemocraticBerl E. PriebeWon(incumbent)	Democratic	15,80468.7%	68.7%
RepublicanDavid J. Hanson	Republican	7,18731.3%	31.3%
Scattered write-ins	Write-in	30.0%	0.0%

Iowa Senate District 8, 1972 to 2024, 1984, every candidate
Candidate	Party	Votes and share	Share
DemocraticBerl E. PriebeWon(incumbent)	Democratic	16,121100.0%	100.0%
Scattered write-ins	Write-in	10.0%	0.0%

Iowa Senate District 8, 1972 to 2024, 1980, every candidate
Candidate	Party	Votes and share	Share
RepublicanRolf V. CraftWon(incumbent)	Republican	15,254100.0%	100.0%
Scattered write-ins	Write-in	20.0%	0.0%

Votes for listed candidates: 22,794
Election day: November 2, 1976
District map: Older district map (1972 to 1981)

Iowa Senate District 8, 1972 to 2024, 1976, every candidate
Candidate	Party	Votes and share	Share
RepublicanRolf V. CraftWon	Republican	12,91656.7%	56.7%
DemocraticRichard R. Nelson	Democratic	9,87743.3%	43.3%
Scattered write-ins	Write-in	10.0%	0.0%

Votes for listed candidates: 24,453
Election day: November 7, 1972
District map: Older district map (1972 to 1981)

Iowa Senate District 8, 1972 to 2024, 1972, every candidate
Candidate	Party	Votes and share	Share
DemocraticH. L. HeyingWon	Democratic	12,16349.7%	49.7%
RepublicanGeorge L. Shawver(incumbent)	Republican	11,99549.0%	49.0%
OtherKenneth V. Fink	Other	2951.2%	1.2%

2024: MEDSL 2024 official precinct returns (individual_states zips), retrieved Oct 28, 2026. Compiled by MIT Election Data and Science Lab (MEDSL) from official returns; not an official source
1972 to 2020: State Legislative Election Returns, 1967-2022 (Carl Klarner, Harvard Dataverse), retrieved Oct 28, 2026. Compiled by Carl Klarner (Harvard Dataverse) from official returns; not an official source

Only part of this chamber is up in a given cycle. Which districts vote on which date is not on file. Last contest in this district on file: 2024.

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Election Wrld. (2026). Iowa State Senate District 8, election results 1972 to 2024. https://www.electionwrld.com/ia/senate/8. Retrieved October 31, 2026.

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Sources

Sources: Census TIGERweb Legislative MapServer (120th CDs layer 0, 119th CDs layer 4, 2026 SLD upper layer 1 and lower layer 2) (US Census Bureau, public domain), retrieved Oct 28, 2026; Open Civic Data division identifiers (census_autogenerated us_sldl/us_sldu and openstates state files); also (sld-recent.json): Open Civic Data division identifiers (country-us) (CC0 (repository); also (sld-recent.json): CC0 1.0), retrieved Oct 28, 2026; Open States people (current) CSVs (CC0-1.0 (Open States people data)), retrieved Oct 28, 2026, compiled by Open States volunteers and staff (rosters from state legislature sites) from official returns, not an official source; MEDSL 2024 official precinct returns (individual_states zips) (Not stated in the GitHub repository (an earlier label said "MIT (repo)", which the repository does not support). MEDSL's Harvard Dataverse records are CC0 1.0, but these GitHub files were not checksum-matched to the Dataverse files, so CC0 is not claimed for them.), retrieved Oct 28, 2026, compiled by MIT Election Data and Science Lab (MEDSL) from official returns, not an official source; State Legislative Election Returns, 1967-2022 (Carl Klarner, Harvard Dataverse) (CC0 1.0), retrieved Oct 28, 2026, compiled by Carl Klarner (Harvard Dataverse) from official returns, not an official source.

District id: ocd-division/country:us/state:ia/sldu:8

DataState data (JSON)Sources: State Legislative Election Returns, 1967-2022 (Carl Klarner, Harvard Dataverse), MEDSL 2024 official precinct returnsData as of Oct 28, 2026