I see the map as a garden. It needs love and care from local mappers who know the area and can look after it regularly. This means editing regularly in the area, as against armchair mapping – of which I do quite a bit (!), but there is nothing like a community of locals taking care of an area.

What areas of the US receive such community love and what areas do not? Digging into the raw changeset dump produces some interesting results.

Methodology

This is what I did :

1. For all changesets, approximate the location of the changeset to the center of the bounding box and geocode the point to the country level – throw out all changesets which are not geocoded to the US and which seem to be over 2 latitudes or 2 longitudes wide (these are mostly programmatic edits)

2. Remove changesets by special users, davehansentiger, milenko, OSMFRedactionbot, bot-mode, woodpeck_fixbot and nhd-import (these were the big import accounts I identified, did I miss any?)

3. Divide up the country into .1 X .1 latitude / longitude squares (this is approximately a 11km X 11km box) and treat each box as a little garden of its own. For each of these of these gardens ask the following questions:

a) how many unique users have made commited a changeset in this area? b) how many unique users have made more than 5 changesets in this area? c) how many unique users have made more than 10 changesets in this area?

1. Once I calculated these three metrics, then I was ready to generate some pretty maps and analyses! I’m presenting some results below.

Findings

1. Here are the top OSM Gardens in the US that are well taken care of in the US.

• Bay Area 64 contributors with 10+ changesets
• DC 53 contributors with 10+ changesets
• Seattle 42 contributors with 10+ changesets

The complete top 10 list can be seen here: http://pastie.org/pastes/8897892/text

1. And here is map of places with at least five contributors commiting more than 10 changesets:

1. Here is a similar map, with major cities marked as airplanes. All the major cities seem to meet this bar of having at least 5 members who have made more than 10 changes. But at the second tier there is a lot of variation. Looking in the south, Alabama, Huntsville and Montogemery and Alamaba all seem to have at least one area that is well taken care of, while cities in Louisiana (Lafayette) or Arkansas seem to have no real communities to speak of. Memphis, TN and Knoxville, TN seem to have very little acitvity – while there seems to be a decent community in Nashville. I think there is a lot of interesting variation here that goe beyond simply saying that places with people are places with contributors.

Going forward

This is very much a work in progress. If there is interest I could compile lists which state more clearly (large) cities that could do with community engagement and others that seem to have plenty going on. I should also figure out how to make these maps in TileMill and have embed them so that people can play around with them.