a short introduction

@tmcw + @aj_ashton / MapBox

OpenStreetMap is a free world map created and owned by volunteers.

'Created by Volunteers'

  1. GPS Traces
  2. Data Imports
  3. 'Armchair Mapping'*

*what we're going to do


Yes! Some of the best data is government-generated and free. The US Census TIGER dataset makes up most of America?

So I should import X?

Maybe! Ask on


OpenStreetMap data rivals commercial providers. In some areas, it's more complete - and in some it's less. But unlike other maps, this one you can improve.

'Owned by Volunteers'

You can download the whole thing:

Or just cities:


Free as in: not only $0, but you can adapt it, download it, print it, and more.

Without asking for permission.

So OpenStreetMap is a free world map owned and created by volunteers.

What's in it?


  • Transport
  • Buildings
  • Rivers
  • POIs
  • Borders


  • Ratings
  • Opinions
  • Historical Data
  • Rasters

everyone sees the same map

the key to understanding openstreetmap: it's a single, global effort. not just a dumping ground for data.


  1. nodes, ways, and relations: primitive types
  2. tags: all data storage
  3. changesets: history

nodes are points

ways are lines & areas

made up of nodes

aka LineString and Polygon

relations are groups

a group of ways → a multipolygon

* no real GIS equivalent...

tags are data

the basic form of a tag:


so nodes, ways, and relations are the basic elements of OpenStreetMap, and each can have data attached to them via tags

one last thing


are our version of history

a changeset is a group of changes

user tmcw changed way #1000, adding a tag and removing a node.

responsibility and reversibility

this answers the question of vandalism: yes, it happens, but we know who does it and we can reverse the changes

that is, everyone has an account