GIS Day 2025 - colourful text overlain on globe

Celebrating GIS Day: Mapping for Everyone

Every November, we celebrate GIS Day - a global event that highlights the power of spatial thinking. Since 1999, it's been a day to share maps, tell stories, and invite others to explore the layers of our world.

Geographic Information Systems (GIS) is more than just a set of technical tools - it's a way of seeing the world. As Nick Okafor, founder of the youth-centered tech nonprofit trubel&co, writes:

'Our world has innumerable layers, everywhere across space and time… Mapping data makes more visible even that which is hidden, which gives it more power.'

GIS helps can help us thoughtfully consider the data, uncover those hidden layers, and understand their relationships. We can use it imagine alternatives to how things are. This 'layered' way of thinking has deep historical roots and continues to evolve alongside technology and human insight.

Early Innovations in Spatial Thinking

Our most iconic early example of using maps to make the invisible visible is Dr. John Snow's use of spatial analysis to trace cholera cases in 19th century London. But he wasn’t the only, or the first, historical example of using spatial thinking to understand our world.

Part of Tabula Peutingeriana, Konrad Miller's facsimile, 1887. Public domain.

The Tabula Peutingeriana, above, visualized roads across the ancient Roman empire - not to scale, but to show connectivity within the road network (similar to a modern public transit schematic).

Al-Idrisi's world map. Public Domain.

In the 12th century, the Arab Muslim geographer Muhammad al-Idrisi created a world map that integrated knowledge from Africa, Europe, and Asia, offering a global perspective that went on to influence cartographers for hundreds of years.

Some Indigenous mapping traditions, like Polynesian stick charts and Inuit tactile maps, use natural materials to represent currents, winds, and landmarks. These tools were passed down through generations as community-driven spatial knowledge systems.

Charles Minard's 1869 chart depicting Napoleon’s 1812 Russian campaign

Charles Minard's 1869 chart depicting Napoleon’s 1812 Russian campaign. Public domain.

In the 19th century, an 80-year-old French engineer named Charles Joseph Minard designed a flow map of Napoleon’s Russian campaign, combining geography and data to tell a devastating story. Meanwhile, Florence Nightingale, the founder of modern nursing, used polar area diagrams (Nightingale rose diagrams) to expose preventable deaths in military hospitals, driving public health reform. These data-driven graphics did more than simply show the locations of things - they informed and empowered.

The Birth of GIS: Seeing the World Differently

In 1963, Roger Tomlinson coined the term Geographic Information System while working on land use planning for the Canadian government. Around the same time, the Harvard Laboratory for Computer Graphics and Spatial Analysis emerged as a hub for early GIS experimentation. Ian McHarg introduced us to the concept of working with stacks of overlain maps (his 'layer cake' method) to reveal patterns and relationships in his 1969 book, Design with Nature. This technique is key to how GIS helps us understand complex systems.

The same year, inspired by this work, Jack and Laura Dangermond founded the Environmental Systems Research Institute, which later became Esri, a leading commercial GIS software company.

Technology Expands the Layers

NASA Earth satellites currently operating (9/2013)

NASA Earth satellites currently operating (9/2013). CC BY 2.0. Image source: AIRS.

The launch of Landsat satellites and GPS during the 1970s revolutionized data collection, enabling accurate and comprehensive mapping of the entire earth and precise location tracking. Open-source GIS software like GRASS broadened access to spatial tools, while national mapping initiatives like the U.S. Census Bureau’s TIGER database laid the groundwork for large-scale digital mapping.

By the 1990s, GIS was gaining mainstream traction. The rise of the internet and cloud computing in the 2000s began GIS's transition away from desktop computers and toward web-based collaboration. The ubiquity of personal smartphones and use of platforms like Google Maps turned everyone into a GIS user.

Many organizations, including governments, took up the practice of openly sharing their data with the public. Digital data libraries proliferated. This increased accessibility and transparency allowed researchers and the public alike to participate in data-driven decision making, and to explore issues that affected them personally.

The Future of Layered Thinking

Today, GIS is merging with artificial intelligence in a field known as GeoAI. Automated spatial workflows can analyze massive datasets (especially satellite and aerial imagery), revealing patterns that were previously hidden. During the COVID-19 pandemic, GIS dashboards helped track the virus and inform global responses, showing how spatial data can support public health and collective action.

As Nick Okafor notes, 'Once someone learns to see and think in layers, it is hard to stop.' GIS encourages critical thinking, experiential learning, and creative problem-solving. It helps communities understand their environments and imagine new possibilities.

GIS as a Tool for Change

Photo: CC BY 3.0 US Mapbox Uncharted ERG

GIS has always been about more than technology. It’s a way of seeing - of examining the layers of our world and the relationships between them. Whether you're a scientist, planner, activist, or student, GIS offers a framework for understanding how things are, and imagining how they could be.

If you'd like to learn more about GIS, check out the resources available from the Map and Data Library website or get in contact.