Your first map.
By the end of this session you will have installed QGIS, loaded two DC datasets, styled them, and exported a finished map. That map goes straight onto the Map Wall with your name on it.
Before you arrive (10 min)
- 1. Install QGIS (free) Download the Long Term Release (LTR) for your OS from qgis.org. It's about 1 GB, so do this on good wifi before the session. Open it once so first-run setup finishes.
- 2. Download: DC wards (GeoJSON) Eight polygons, one per District ward. Right-click → Save Link As if it opens in the browser.
- 3. Download: Metro stations (GeoJSON) Forty points, one for every Metrorail station in the District. It's the same data behind our live atlas.
Put both files in a folder you can find, e.g.
Documents/spl-workshop-1/.
Part 1: load the data (10 min)
Open QGIS → Project → New. Then drag
wards.geojson from your file browser anywhere onto
the QGIS window. A map of DC appears. Drag
metro-stations.geojson in the same way.
Look at the Layers panel (bottom-left). Two entries, which is the core idea of GIS: your map is a stack of layers. Drag metro-stations above wards if it isn't already (points draw on top of polygons).
Right-click the wards layer → Open Attribute Table. Every shape on the map is also a row of data. Close it again. That table is the reason this counts as an information system rather than a drawing.
Part 2: style the wards (15 min)
Double-click the wards layer → Symbology (left sidebar of the dialog).
At the top, change Single Symbol to
Categorized. Set Value to
name, pick a color ramp you like, press
Classify, then OK. Eight
wards, eight colors.
If the colors are too strong, reopen Symbology, click the Symbol above the classes list, and drop Opacity to about 50%. Muted fills will read better once the stations go on top.
Part 3: style the stations and add labels (15 min)
Double-click metro-stations → Symbology. Make the marker a white circle, size 2.5 to 3 mm, with a dark outline (Stroke color). It should start looking like a transit map.
Now labels: with the same dialog open, switch to
Labels (left sidebar) → change No
Labels to Single Labels, set Value
to name, font size ~8, and under
Buffer tick Draw text buffer (white,
0.7 mm). Press OK. If it comes out cluttered, that's normal.
Labeling takes practice; keep the labels on or turn them off.
Part 4: export your map (15 min)
Project → New Print Layout, name it anything, OK. In the layout window: Add Item → Add Map, then drag a rectangle across the page. Your styled map appears.
Add a title: Add Item → Add Label, drag a box, and type a descriptive title such as “Metro Stations by Ward,” then bump the font in Item Properties. Add another small label with your name and “Data: DC Open Data” on it, because cartographers sign and cite their work.
Layout → Export as Image… → save as PNG. That's a map you made.
Publish it
Post it on the Map Wall. The how-to is in ADDING-YOUR-WORK, and any officer will walk you through the pull request.