Our maps don’t know where you are – tags

Our maps don’t know where you are – tags

Despite their ubiquity in modern life, maps have a distinct set of challenges that set them apart from other visualizations, such as charts or tables.

Even by the standards of the large data sets we often work with at The Markup, geospatial data is huge and complex, because the physical world it encapsulates is big and messy.

A good map summarizes and simplifies the area it represents, without distorting or destroying it. As if this task wasn’t difficult enough, any aspiring cartographer must also contend with the laws of geometry, which make it impossible to flatten a spherical Earth (technically an oblate ellipsoid) onto a two-dimensional plane without some compromise.

At The Markup, we’re adding one final hurdle to this obstacle course: our promise of privacy.

The Markup pledges to collect as little information as possible about our readers. We do not use tracking cookies on our website. We screen third-party services before including them in our articles or elsewhere on our website. Many of them include tracking or analytics devices that may collect data about our readers. This may be standard on a lot of websites, but we don’t use it.

As a result, when we decided to map the addresses we’d collected in our investigation of internet speeds across the United States, we ran into a familiar problem.

Investigative journalists Leon Yin and Aaron Sankin collected more than 1 million Internet bids in 45 U.S. cities and found that the four largest ISPs routinely charged customers the same price for vastly different Internet speeds (a practice called “tier flattening”).

By analyzing the download speeds providers offered to these addresses using census demographics and digital historical maps, Lyons and Aaron found that ISPs disproportionately offer the worst deals to neighborhoods with the lowest concentration of white residents and lower middle incomes.

We wanted to plot our findings on a map, so readers, activists, and other journalists could pan across their city, zoom out to street level, and see the internet speeds in each individual home.

First, we turned to Mapbox, the industry leader in creating and publishing maps online. But when we included a map from Mapbox on our staging website, we found that it was for a tracker that could not be disabled without violating Mapbox’s terms of service.

This wasn’t the first time we’ve encountered this issue with third-party services. Longtime readers of Tags may remember how long it took us to find an email provider that allowed us to disable trackers that would have been sent in our newsletters. We also had to build our own privacy-protecting video player, donation platform, A/B testing tool, and more.

We went looking for a tracker-free map and weighed our options. We use Datawrapper for many of our basic charts and maps, but Datawrapper only supports up to 100 points on a symbol map. We had to draw over 900,000 titles.

We surveyed the broad landscape of mapping solutions, examining services like Felt and Protomaps. In the end we settled on MapTiler, a Swiss company. MapTiler offers a flexible—and, most importantly, tracker-free—set of tools for hosting and designing map data. Their privacy policy clearly documents what information they collect and where, even specifying that they only keep visitors’ IP addresses in their memory for a short time before destroying them. Unlike some proprietary products, MapTiler derives its base map from OpenStreetMap, an open source collection of geographic data.

As part of the investigation, Leon collected addresses from two open source datasets, OpenAddresses and NYC OpenData, both of which come with latitude and longitude coordinates assigned to each street address. We used the Tippecanoe command-line tool to convert these addresses into vector tiles, breaking the address locations into smaller subsets that can load quickly in the browser.

Finally, we used MapLibre GL JS, an open source derivative of the Mapbox map library, to display the base map and address boxes on our website. We added features like a tooltip with details for each address, and filters to isolate neighborhoods by demographics.

The final result, published on May 11, reveals stark disparities in internet speeds in major urban areas across the country. We hope this will open new vistas for coding maps.

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