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citysize (WIP)

An interactive map that lets you accurately compare geographic features like countries, cities, states and even buildings inspired by and powered by

How it works

The search box only returns items from OSM Nominatim with GeoJSON polygon data, when you select a search entry the app with will convert the GeoJSON data into a basic outline it can be rendered to the map. The interactivity and the (mostly) accurate projection of the GeoJSON outlines on the map is possible with mapbox-gl-leaflet and leaflet-truesize.


  • Add location stats UI, population, square meterage, etc.
  • Add VS mode, to compare two places directly without having to drag them around.
  • Add support for Mulitpolygon GeoJSON.
  • Add support for pasting arbitrary GeoJSON data.
  • Add GeoJSON simplification option.
  • Add basic configuration settings, tileset theme, enable/disable FlyTo, etc.

Bugs & Q&As

  • Larger GeoJSON objects (like Russia) don't render.
    • Fixable by passing the polygon data through a minifier prior to render.
  • Some outlines duplicate when there are multiple outlines already on screen.
    • Not sure why by it seems to be caused be excessive zooming.
  • Some regions (like Spain and Tokyo) are rendered as small islands or missing large regions.
    • The flattenGeojson function only supports the first instance of a coordinates array in a GeoJSON, support for multipolygons is a TODO.
  • Dragging certain larger countries around is laggy.
    • Fixable by passing through a GeoJSON minifier because translating 100,000+ points across a map in real time is hard.
  • Why is the search is funky?
    • Turns out emulating Google search isn't that easy, I'm trying my best okay??
  • Why doesn't this specific exist when I search for it?
    • It's either not on OpenStreetMap or it is but doesn't have any GeoJSON data with it.
    • Example of a place with GeoJSON data, the first result is a point where the point lays between two latitude and longitude points (can't be rendered as a shape), the second result contains polygon info under "geometry": {"type": "Polygon",} that effectively tells the map to connect the dots against the array of points.

react-boilerplate / dependencies

Made on top of a create-react-app instance, depends on:

  • axios
  • leaflet
  • leaflet-truesize
  • mapbox-gl
  • mapbox-gl-leaflet
  • node-sass
  • react
  • react-dom
  • react-leaflet
  • react-scripts

Setup and Run

Clone this repository:

git clone & cd citysize/

Start the local Webpack Dev Server:

yarn start

To lint all JavaScript files in the src folder:

yarn lint

To build and output static HTML and JS files:

webpack -p


A projection-accurate interactive map that lets you compare the sizes of cities, countries and even buildings.






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