Gov 2.0 guide to open source custom map design using TileMill


This week, Development Seed announced the release of a full-featured map design studio that enables web developers to rapidly generate gorgeous custom maps. Based upon open source technologies and funded in part by a generous grant from The Knight Foundation, TileMill dramatically increases the accessibility of custom map generation for enterprise users, including the government. By decreasing the sunk costs required to generate custom maps and at the same time increasing the performance of these solutions, TileMill also paves the way for the next generation of geospatial products capable of meeting the open data imperative.

Why is TileMill Disruptive?

To understand the value TileMill provides, one must understand the existing custom mapping landscape. Even in the Web 2.0 world, those who desire custom maps and geospatial web services (not just a generic Google Maps embed) often need to be able to justify exponential increases in costs and/or schedule for their projects.

TileMill is a game changer because it dramatically lowers the barrier to custom map generation and makes it possible for almost anyone (from a policy analyst to a web developer to a GIS analyst) to quickly generate professional looking, custom maps. It does so by:

  1. Leveraging an innovative programming environment that requires no more than the minimal programming abilities expected for web development (ex. CSS-like language);
  2. Supporting a community that is committed to making validated data sets more accessible for its users.
TileMill Custom Map Design Studio
TileMill Custom Map Design Studio

Rather than serving as “a general-purpose cartography tool, TileMill focuses on streamlining and simplifying making beautiful maps.” This means TileMill is not planning to go head-to-head with proprietary GIS systems (ex. ESRI ArcGIS or AutoDesk GIS Design Server). Instead TileMill targets a broad set of audience needs not well met (or likely to be met) by existing products. It does so by helping the average web developer overcome their own challenges: a lack of core skills (software, training, and experience) and time required to generate complex custom maps from traditional geospatial information system (GIS) solutions. From this perspective, TileMill clearly augments and expands both the geospatial and web development marketplaces.

What Makes TileMill Innovative?

In the closed and open source geospatial community, there are many solutions and standards available to developers. What differentiates TileMill is not so much that it is free and that it is based upon a number of open source standards (both of which are true). Nor is it just the fact that a broad audiences of traditional and nontraditional GIS users find the world of custom map making to be easy to use and accessible with TileMill. In the world of Enterprise IT, where innovation often is judged on its technical merits, it’s what is under the hood that still matters most. Thankfully, TileMill does not disappoint.

From the technical perspective, TileMill’s use of Carto, coupled with its deep integration with Mapnik, helps to set it apart in the marketplace:

  • Inspired by Cascadenik, Carto is a CSS-like map styling language based on less.js. It is custom designed to make geospatial mapping more accessible to the average web developer as well as to generate significant performance savings over comparable languages. For example, compared to Cascadenik, typical Carto stylesheets compile 4-5 times faster (usually in less than 100 milliseconds).
  • Mapnik is a OpenSource C++ toolkit for developing mapping applications and integrates with the node.js, a super fast non-blocking server side javascript platform. Thanks to Mapnik’s reference project, the TileMill editor can even highlight correct attributes and suggest corrections when values are invalid.
Open Data at the World Bank with map tiles baked using TileMill
Open Data at the World Bank with map tiles baked using TileMill

How Can TileMill Help Government Agencies Meet the Open Data Imperative?

With TileMill now fully integrated with other MapBox solutions and supporting shapefiles, GeoTIFF rasters, simple KML and GeoJSON, as data pulling from a local disk or from Amazon S3, it is clear that the MapBox solution set can meet a broad range of enterprise user needs (including those of government agencies and federal contractors). This was recently validated by a major media organization, who leverages TileMill to stylize U.S. Census data for their web site:

Beyond this example, TileMill provides limitless options for new lost-cost, high-impact solutions designed to meet the open data imperative. These include a wide range of domestic and international public policy challenges that require new mobile apps, web services, analytical tool sets, and real-time monitoring technologies. From this perspective, the future of open data looks more promising than ever with the release of TileMill.

Appendix: Guide to MapBox Tools and Services

In evaluating TileMill, it is important to consider the larger MapBox set of solutions. At present, MapBox is composed of the following tools and services (reproduced with permission from the MapBox web site):

U.S. Census data map styled with TileMill by Chicago Tribune
U.S. Census data map styled with TileMill by Chicago Tribune
  • MapBox on Apps.Gov provides federal agencies with the ability to freely use MapBox map tiles as a software-as-a-service solution.
  • MapBox.Com hosts free custom designed map tiles, detailed documentation, and open source tools to help users easily build customs maps for their websites.
  • MapBox for iPad enables Apple users to interact with their custom maps (including visualizing their KML and GeoRSS data) entirely offline.
  • Maps on a Stick provides Apple and Windows users with the ability to distribute their custom maps using only removable media – a critical asset in low bandwidth and mobile computing intensive environments.
  • MapBox Hosting offers paid premium cloud-based tile hosting for MapBox users. This ensures that organizations can quickly scale their geospatial capabilities to meet their needs.
  • TileMill is a tool for cartographers to quickly and easily design maps for the web using custom data. It is built on the powerful open-source map rendering library Mapnik, the same software OpenStreetMap and MapQuest use to make some of their maps. TileMill is not intended to be a general-purpose cartography tool but rather focuses on streamlining and simplifying making beautiful maps.
Pakistani flood relief map with MapBox
Pakistani flood relief map with MapBox

TileMill full video overview:

About Michael Walsh

Michael Walsh is a well known writer and speaker on open source and proprietary software. In addition to working at Microsoft and in Open Source Communities like MapBox, Michael previously served as a regular contributor to TechNet Magazine. Presently, Michael is completing Post-MA classwork at The Johns Hopkins University SAIS. Feel free to contact him at

13 Responses

  1. Anonymous

    I’ve seen something like this through a custom map technology webinar at Maybe there was some collaboration. impressive!

  2. […] Gov 2.0 guide to open source custom map design using TileMill This year, the focus is on how governments and nonprofits can leverage the new custom map design studio (TileMill) from MapBox to address public policy challenges. It is an especially interesting story given the increasing demand for custom maps for websites, web services, and mobile applications. (tags: gis mapbox tilemill readlater) […]

  3. Elizabeth

    I don’t think the two are related in any way. Unless I am missing something, Erichson looks like a company that provides ESRI GIS consulting. This article discusses an open source map design studio unrelated to ESRI ArcGIS. Am I missing something? Is this spam?


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