Media Markets: Daily Kos Elections is pleased to present a brand-new version of one of our most useful resources: our spreadsheet detailing the overlaps between the nation's congressional districts and its media markets. This database, developed by contributing editor David Jarman, is fully updated for the new districts created as a result of the most recent decennial redistricting process that will be used in the November midterms.
And knowing how these new district lines intersect with the country's 210 "Designated Market Areas" or DMAs (as defined by Nielsen Media Research) is critical to understanding how campaigns, PACs, and parties spend their money on the single biggest expense for most House races: advertising on broadcast television.
Love political ads or (more likely) hate 'em, their ability to reach massive numbers of voters at once will always make them a popular choice for many campaigns. In particular, the people who are likeliest to be watching broadcast TV—older voters—are also often the most reliable voters. And so-called "event television," like major sporting events that most viewers tend to watch live, offer large captive audiences who can't simply fast-forward through advertisements.
But how ad dollars translate into congressional races isn't especially straightforward, because buyers of TV time purchase that time at the level of media markets, which represent regions where viewers can expect to see the same broadcast television stations and in almost all cases bear no resemblance to the lines that states draw for their districts. As a result, every congressional district either takes up just a part of a market, or covers all or part of multiple markets.
So when, for instance, you see a super PAC announcing a $1 million reservation in the Detroit market, what exactly does that mean? Well, that’s exactly what our spreadsheet can tell you! It turns out that the Detroit DMA includes the entirety of five congressional districts and parts of three others. But as it happens, only two of those districts, Michigan’s 7th and 10th, are actually competitive this year. (Another Daily Kos Elections data set offers a helpful guide: our calculations of how the 2020 presidential election would have gone under the new maps, which show both of these districts as very evenly divided.)
And as we can see further, only the 10th is located entirely in the Detroit market (which, it should be noted, is much bigger than the city itself), while just 31% of the 7th is in Detroit, with the majority in the state capital of Lansing. Standing on its own, therefore, this reservation would likely be targeted at the 10th. However, it’s more typical to see major spenders book TV time across multiple markets at once, as the pro-Democratic House Majority PAC did in March when it made reservations in four different Michigan-based media markets—broad enough coverage to sweep in the 7th, as well as the Grand Rapids-based 3rd and the Flint-based 8th.
This data is also useful for grassroots donors because it can help you discover which districts allow campaigns to advertise most efficiently, where “efficiency” is defined as not having to spend much money reaching viewers who can’t actually vote for you. This is a huge problem for candidates in expensive media markets like New York City’s, where not only are ad prices the highest in the nation, but, at best, just 3.5% of the DMA’s 22 million inhabitants even live in your district.
On the flipside are districts like Oregon’s 4th, a competitive Democratic-held open seat along the southern Willamette Valley and the state’s south coast: 96% of its population is in the Eugene media market, while 89% of people who live in the Eugene DMA also live in the 4th District. Advertising on TV here can therefore be very effective, especially since prices in Eugene, which is the 113th-largest market in the country, are quite moderate.
For more on this one-of-a-kind resource, please check out Jarman’s detailed post on the subject. There you’ll also find a discussion of related spreadsheet: our database of presidential elections broken down by media market, which stretches all the way back to 1960. And to bookmark our congressional district-media market tables, just click here.