Why do overlapping urban dots on election dot maps create a better representation than graduated color schemes?

The author explains that while overlapping dots in cities technically underreport the raw number of urban voters, this visual undercount is acceptable because it preserves the true proportional distribution of votes across the map. Additionally, the author notes that this approach is justified given the electoral college's structural bias toward smaller rural states, making the visual representation more aligned with actual political power distribution.

What specific voter diversity does traditional red-blue election mapping fail to show?

Traditional binary color-coded maps obscure the fact that even in the most partisan regions of the country, significant numbers of voters from both parties exist. By depicting entire regions as uniformly red or blue, these maps create a false impression of America as a strictly divided nation and hide the nuanced political composition within each region.

Data Tuesday: 20 Years of US Elections

Reason #1000 dot maps are a superior format

By Peter Banks · July 15, 2025 · Updated August 24, 2026 · Read on Substack

Summary: The author advocates for dot maps as a superior method for visualizing US presidential election results from 2000-2020, arguing they overcome two critical flaws in traditional election cartography. Traditional red-blue maps misrepresent America as uniformly one color while obscuring significant minority party support even in partisan strongholds; graduated color schemes similarly fail to show population distribution. Dot maps solve both problems by representing each 1,000 voters as a single dot, revealing both political diversity and the true concentration of the electorate in urban areas.

In my quest to get people to use more dot maps, I’ve decided to show a third example where I think the style is uniquely good. Namely, the U.S. election presidential election results for 2000-2020. Currently I think election maps in the US have two issues.

First, they tend to show America as a “red” vs. a “blue” country. With maps like this:

A Mostly Complete Map of Counties in the 2024 Presidential Election : r/MapPorn — 2024

There is, of course, a grain of truth to these maps, but they also obscures the fact that even in the most partisan parts of this country you still have significant numbers of voters from both parties.

But even if you fix this and have a more graduated color map like this one:

America's counties are less purple than they used to be

You still fail to communicate where the electorate actually lives!

Well, luckily the dot map once again solves all of these problems.

This data was collected from the MIT Election Dataset. They have updated data from 2000–2024; however I’m using an earlier download of just the data through 2020.

Each dot represents 1,000 people. I found this to be a sweet spot, nevertheless it still underreports the true size of urban voters, their dots are overlapping. Since we have a bias to smaller rural states in the electoral college I think this is mostly okay. I have written the code so that it attempts to match the distribution of votes in the city visually, thus color accurately communicates the proportionality even if dots are overlapping.