ICYMI, here is a VeloNews article that provides a great introduction to the Close Call Database. Read it here.

Welcome to the Close Call Database

A Community Project for Safer Cycling

Geographic Distribution of the Close Call Database Community

The database's effectiveness increases with membership and coverage. So if you are a cyclist and you have read this far and still haven't joined . . . then you are not helping! At all! Not even a little bit!  This thing only works if you team up with the other cyclists in your area.
The map below shows the location of currently registered users. You can see that most users are concentrated in the United States and Great Britain but the service also has traction in other parts of the world. If there is nobody in your country or area yet don't be discouraged: every single country and location started off at zero. So just sign up, and encourage your cycling buddies to do the same. To get the most out of this service, you want to encourage other cyclists in your area to join. That's how you get 'eyes and ears' out on the road.
This map will allow you see your the current size of the network in your area. To do so, click on the round "cluster target" closest to the area that where you live. The reporting zone will typically encompass a 60 mile radius, so the numbers you see after two clicks into the map in your area is pretty representative of the number of other cyclists in your "network", but you can drill in deeper. If you drill in all the way, the final numbers are assigned to a city or zip code's geographic center.