Welcome to the third and final part of our series on maps and data visualizations in advance of the 2024 U.S. General Election (if you’re just catching up, here are parts one and two). Today, we’ll close with discussion of Congressional races and the electoral college.
I’m just a bill
We’ve mostly discussed the presidential contest so far, but there are other races besides the presidency to watch out for in the general election. State and local races can certainly help us better understand polling trends and may provide insight into presidential election returns as they come in.
This article from Al Jazeera gives an excellent overview of all the major contests in this election. Without any mention of how each race is leaning or even who is running, they put into context what positions are up for grabs and which party currently holds each one.
One important distinction of the Senate component of each general and midterm election is that only ⅓ of Senate seats are up for reelection at a time. In the other chamber, all Representatives are up for reelection every 2 years. Not knowing these stipulations when looking at Congressional projections can be confusing!
Placing important context right next to a recognizable graphic, especially one that is color-coded with a clear legend, really gives the reader everything they need to understand the situation. It’s nice how this graphic uses the semicircular seating chart we’re used to seeing for each chamber of Congress, too.
FiveThirtyEight’s Senate version of the probability breakdown provides a clear depiction of the probable overall outcome of this election, as well as a peek into their methodology for generating such a forecast. Using a data-driven sentence that is color-coded by party and features simple terminology makes it very clear what a reader should take away here: they ran 1000 simulations and it is far more likely that Republicans will take the Senate. I don’t even need to look at the corresponding visualization to understand this – sometimes words are enough to get the point across.
In 2024, it happens that more incumbent Democrat seats are up for reelection than Republican seats, which you can see very clearly in the legend below. This year’s Senate contests appear to have only one true toss-up, which explains why the projection is much more one-sided than the Presidential contest. A legend that doubles as a data visualization really takes things to another level.
This map uses color-coded lock icons for seats that are not up for election this time around, which I find to be very helpful. The locks may give us some insight into where each party might be able to gain ground in the midterms in 2026 (i.e. states that have split Senate representation). The information about caucusing provided in the legend at the bottom is also really helpful, as the Senate race is not always as straightforward as Democrat vs. Republican. It’s important to remember that Independents may be a wildcard on certain issues and can’t always be counted on to vote with the party they most closely align with.
As you might expect, the House contest is considerably closer than the Senate contest, but not quite as tight as the Presidential race.
There are very few toss-up contests in the House as well, as you can see below. Again, the legend tells me that, overall, it looks like the Democrats are possibly going to pick up some seats, as there are fewer red leaning/likely/solid seats than red seats in the current House.
WaPo’s House cartogram highlights the races to keep track of, which is helpful in a sea of 435 simultaneous races, each with its own complexity. Most House races include an incumbent, who statistically has an advantage over a challenger, so highlighting the party that currently holds the seat is helpful. Emphasizing incumbency here instead of who is forecasted to win the seat is a different perspective than the FiveThirtyEight cartogram above. It’s useful to have both – context is essential to understanding these races.
They follow up the cartogram with a simple visual comparing those highlighted races and how they lean right now. With this comparison, I can quickly see that there’s one likely flip from red to blue and 26 (!) toss-ups. Again, because of how quickly things change and how limited consistent polling is for House races, I appreciate how this graphic leans into uncertainty. It’s not always responsible to forecast or project a winner when we know the underlying data may not be of the highest quality.
As an aside, notably missing from these maps are Senators or Representatives for D.C. Despite otherwise being full U.S. citizens who pay federal income taxes, those living in D.C. still have no representation in Congress.
Electoral math
In our current political system, the popular vote is essentially meaningless. It’s all about the Electoral College. This is an area where media outlets have to work to communicate the differences between the popular vote and actual electoral outcome to the American people.
I’m glad to see FiveThirtyEight has kept many of the wonderful visualizations from the last election cycle, including the Path to 270 (aka “the snake”). The snake shows electoral votes by state in a clear, easy-to-follow visual brought to life with a straightforward color palette.
The colors here represent the forecasted margin of victory, with darker colors representing more partisan states. Longer sections of the snake represent states with more votes than shorter sections. It’s easy to see how much of an influence each swing state has on the total count and which states are trending in either direction at the current moment in time.
There are a lot of similar visualizations in this series so we should take a moment to appreciate how creative the snake is as a form. Coming to the table with a new or nonstandard form really seems to encourage readers to engage with it meaningfully (who could forget NYT’s needle or WaPo’s political wind map). Whether successful or not (I think this one is), it’s refreshing to see variety in election visualizations.
Also included in FiveThirtyEight’s election forecast is a probability map/cartogram combo that uses color palette, saturation, and patterns to quickly communicate the state of the race. Unlike the Path to 270, this visual clearly picks out the swing states, using a purple hatched pattern (which we love for design accessibility) to indicate that they are currently toss-ups. It’s great to see the definitions for each categorization clearly in the legend, too.
This map is nice because it doesn’t immediately assign a prediction to toss–ups; instead, it encourages the reader to investigate for themselves. Election maps are so often an attempt to capture an ever-changing state of play at a particular moment in time, so leaving some ambiguity here by default is a smart way to avoid misleading the reader. There is a lot of uncertainty in elections and it’s okay to lean into that!
If you prefer a guided exploration of possible outcomes, this article from WaPo does a nice job of sketching out eight possible scenarios for Election Day. Instead of leaving the reader to figure out, “if this one goes red and this one goes blue, then xyz needs to happen to get to 270,” they’ve done all the work for you.
These maps illustrate the concept of regionality nicely. Geography matters! Performing well in one state in the Sun Belt may mean that candidate will perform better elsewhere in the Sun Belt, for example. There are a few cases where a candidate only needs to win a certain region in order to meet the 270 threshold, assuming the non-swing states fall as predicted.
In this example, Harris can win the Rust Belt and not worry about the other swing states at all. This might help explain campaign stops and why some swing states get more attention than others. After all, you only need 270 to win!
NPR has a similar version of this regional-focus map, but they really boil it down to two scenarios: Harris must win the so-called “Blue Wall” or one of Pennsylvania, North Carolina, or Georgia. That feels pretty simple and easy to understand! By simply fading one the other states out, you can quickly see which races are critical in each scenario. Information for all states is still immediately available, though, for context.
We absolutely love a cartogram, especially for maps where MAUP (the modifiable areal unit problem) is prominent like it is for U.S. elections. A quick aside for some geography 101:
Election coverage historically has relied a lot on the red and blue map to “explain” election returns, though they leave a lot to be desired. Put simply, the size of a geography does not always equate to its impact. For example, California and Montana are similar in size, but California’s electoral impact (54 electoral votes) is 9x Montana’s (4 electoral votes). Cartograms visually explain the size to weight discrepancy in such a way that geographic relationships like regionality are still visible. It’s always nice to see a cartogram as the primary visual when MAUP is a concern.
By including a traditional map as well, a layperson can still understand the electoral map without needing to learn a completely new form. Ideally, having both will help anyone new to cartograms understand them a bit better.
Election Day
If you’re still reading this, you’re probably anticipating this feeling on the morning of November 6th:
Now more than ever, no matter the flaws and complexity in our system, it’s important that the people’s voices are heard. If you’re feeling (understandable) election anxiety, Vox has put together some coping strategies that may help.
In a month or so, we’ll follow up with some visuals that help explain the election returns and exit polling (see our similar post from 2020). Until then, make sure you’re registered to vote and have a plan for Election Day.
