Eleventh in a series interpreting the results of Iowa’s 2024 state and federal elections.

Many factors helped Iowa Republicans expand their already large state legislative majorities in 2024. Two of the most important were Donald Trump’s dominance in the presidential race, and the continued decline in ticket-splitting.

By my calculations, Trump carried 71 of the 100 Iowa House districts, up from 63 state House districts the last time he was on the ballot in 2020. In all four Democratic-held House districts that flipped this year, voters preferred Trump. That helped Republican Ryan Weldon defeat State Representative Molly Buck in House district 41 (Ankeny), David Blom defeat Sue Cahill in House district 52 (Marshalltown), Jennifer Smith defeat Chuck Isenhart in House district 72 (Dubuque), and Christian Hermanson win the open House district 59 (Mason City).

Trump also carried 20 of the 25 state Senate districts that were on the ballot, including both where Democratic incumbents lost: Mike Pike defeated Nate Boulton in Senate district 20 (eastern Polk County), and Dave Sires defeated Eric Giddens in Senate district 38 (mostly located in Black Hawk County). The only Iowa GOP lawmaker to lose in 2024, State Senator Brad Zaun, faced Matt Blake in a district where voters preferred Kamala Harris for president.

Ticket-splitting used to be more common in Iowa. Republicans maintained control of the state House in 2012, even as Barack Obama carried 61 of the 100 districts that year. (No wonder few observers expected Iowa’s hard shift to the right, beginning in 2016.)

But in 2020 and again this year, only seven Iowa legislators managed to win in districts where voters preferred the other party’s presidential nominee.

I calculated the 2024 numbers using certified precinct-level vote totals from the Iowa Secretary of State’s election results website. Figures on the 2020 presidential vote in each district come from the Iowa House and Iowa Senate maps Josh Hughes created in Dave’s Redistricting App.

This post covers the six Iowa House members and one state senator in descending order, by how much they outperformed the top of their own party’s ticket.

The Daily Kos Elections team performs an incredible public service every two years, calculating top-ticket results for every state legislative district in the country. Last week the staff published raw vote totals and vote shares for Joe Biden and Donald Trump in all 100 Iowa House districts and 50 Iowa Senate districts.

Take my advice and bookmark that spreadsheet, as well as an updated Daily Kos Elections spreadsheet showing how residents of each Iowa legislative district voted for president in 2012 and 2016, for governor in 2014 and 2018, and for U.S. Senate in 2014. Even though Iowa’s state legislative boundaries will soon change, the data will remain useful as evidence of changing voting patterns.

For today I want to dive into crossover voting in Iowa, which was the focus of a Daily Kos Elections post on July 26. Ticket-splitting is rarer now than it used to be, but six current House members won last November, even though their constituents preferred the other party’s presidential candidate. Four sitting state senators represent districts that voted for the other party’s presidential candidate in 2020. However, only one of them was up for re-election last year. We can’t know how the other three would have performed compared to Trump or Biden.

This post covers the legislators whose districts went the other way for president, with thoughts about how each House or Senate district might change on Iowa’s next political map.

More Iowa women are running for office in 2018 than ever before, which could lead to record numbers of female state representatives and senators next year.

However, in other meaningful ways, Iowa’s legislature could become less diverse after the November election.

Now that the deadline to compete in the Democratic or Republican primaries has passed, the field of candidates is set in most of the 100 Iowa House districts and 25 Iowa Senate districts that will be on the ballot this fall.

It’s time for a first look at chances to increase diversity in the state legislature for the next two years. The proportion of white lawmakers is unlikely to change, while the proportion of women could move in either direction.

The filing period for general-election candidates closed on August 15. You can view the full candidate list for federal and state offices on the Iowa Secretary of State’s website. John Deeth briefly reviews all 100 House races here. Next month, I’ll be posting on the most competitive Iowa House races.

For today, I’m interested in what appears to be a pattern of Republicans letting Iowa House seats go in battleground Iowa Senate districts. I suspect a strategy is in play to depress GOTV in the more Democratic halves of these districts.  

In any given general election, roughly a dozen or two of the 100 Iowa House districts are in play. A first look through the list of candidates who qualified for the primary ballot suggests that this year, fewer Iowa House districts will be competitive than in 2010 or 2012. Republicans have failed to field a candidate in 32 of the 47 Democratic-held House districts. Democrats have failed to field a candidate in 26 of the 53 Republican-held House districts.

Although a few of these districts may see major-party candidates nominated through special conventions after the primary, it’s rare for late-starting candidates to have a realistic chance to beat an incumbent. (That said, two Iowa House Democrats lost in 2010 to candidates who joined the race over the summer rather than during the primary campaign.)

After the jump I’ve enclosed a full list of the Iowa House districts left unchallenged by one of the major parties. I highlighted the most surprising recruitment failures and what looks like a pattern of uncontested House seats in Senate districts that will be targeted by both parties, which may reflect a deliberate strategy. House incumbents with no fear of losing may slack off on GOTV in one half of a Senate district where every vote may count.

A future post will focus on the ten or fifteen Iowa House races likely to be most competitive this fall.