A Geographic Information System is software for asking questions with maps. It stores the world as layers — terrain, boundaries, roads, incidents, anything with a location — and lets you stack, compare, and analyze them.
Almost every dataset that matters to policy has a where attached. GIS is how you use it.
Hover the stack to pull the layers apart.
GIS turns vague debates into answerable questions. A few of the kind it settles:
Buffer the route, join census blocks, count the people. Transit equity stops being a hunch and becomes a number.
Overlay grocery locations, walking distance, and income data — the gaps draw themselves.
Compare satellite imagery over time at a military site, a port, a border. Open-source analysts do this daily.
Epidemiologists, urban planners, campaign strategists, climate scientists, journalists, humanitarian responders, intelligence analysts — different fields, same core skill.
The tools are free and the data is public. The whole path from zero to your first published map:
The industry-grade open-source GIS — free, no license, runs on anything. Download it at qgis.org.
DC publishes hundreds of clean datasets at opendata.dc.gov — wards, transit, housing, trees, crime. Load one and you have a map.
Our Zero-to-Map workshop series takes you from install to analysis in four sessions — no experience assumed. Join the lab to get the schedule.
Members ship their work on the SPL Atlas and the Map Wall — with their name on it.
