Anyone who’s worked on urban policy, especially in rapidly growing cities, knows there’s always more going on than the maps let on. The neighborhoods that never quite make it onto official plans—informal settlements, slums, whatever label you use—are often economic engines in their own right. The question isn’t just where these communities are, but how they actually function. And while traditional statistics have a hard time catching up, the combination of ISIC-informed business data and new tech offers a way forward.

 

At first glance, applying something as bureaucratic as the International Standard Industrial Classification to informal settlements feels a little odd. These areas are, almost by definition, off the books. Businesses don’t register, employment goes unreported, and even the street names might be improvised. Yet, if you look closely, patterns begin to emerge. Many informal businesses—food stalls, repair shops, household service providers—mirror categories that exist in the formal sector. For example, ISIC 4799, “Other retail sale not in stores, stalls or markets,” is about as close as you get to describing the sprawling street vending and microservices typical of these neighborhoods.

 

This is where a bit of creativity comes in. Rather than relying on administrative records, analysts can use household and local surveys, sometimes layered with municipal data on known business locations, to build a proxy map of economic activity by ISIC category—even in unregistered zones. The result isn’t perfect, but it provides a common language to talk about what people actually do to make a living. That, in itself, is an advance.

 

But mapping is more than coding. Remote sensing—satellite imagery, aerial photography—has become a mainstay for identifying informal settlement growth. Changes in roof materials, new structures in previously open land, shifts in the night-time light footprint: these signals offer clues about where urban expansion is taking place, often faster than local officials can track. What’s more interesting, though, is what happens when you combine this spatial data with the ISIC-based economic proxies.

 

Imagine overlaying a map of night-time lights with the estimated locations of informal retail and service activity. Are there new clusters appearing along certain transport lines? Is economic activity shifting from one part of the city to another as settlements grow or contract? These questions, which used to be answered by best guesses and anecdote, are now coming within the reach of data-driven analysis.

 

There’s more. The rise of mobile phones, and with them digital traces of daily life, adds another layer of insight. Mobile phone usage patterns—call volume, location data, even mobile money transactions—can reveal areas of economic concentration that traditional surveys miss. Utility data, such as electricity or water usage, sometimes offers a back-door indicator of both population and business intensity, even where meters are unofficial or shared.

 

The magic, if you can call it that, comes from integrating these disparate sources. A neighborhood with a sudden spike in mobile phone traffic, a jump in electricity use, and signs of new informal businesses (even if only estimated through ISIC proxies) is probably experiencing an economic surge, regardless of what the zoning map says. Conversely, a drop across these indicators could be an early warning of economic decline, displacement, or even unrest.

 

Of course, this kind of analysis is full of caveats. None of the data sources—ISIC proxies, remote sensing, digital footprints—captures the whole picture. There are always gaps, false positives, or changes in behavior that escape measurement. The best analysts treat their maps as living documents, meant for updating and debate, not as definitive truth.

 

Still, the shift is profound. By bringing ISIC-based economic logic into the study of informal settlements, cities can move beyond seeing these neighborhoods as mere problems to be solved. They become recognized, instead, as sites of economic adaptation, ingenuity, and potential. That, in turn, opens up new possibilities for targeted infrastructure, financial services, or policy support—ideas rooted in real patterns of work, not just the absence of formality.

 

In the end, the act of mapping isn’t just about what’s visible from above. It’s about illuminating the real, often hidden, economies that keep cities running—one food stall, phone call, and lightbulb at a time.