This was fun. I've been climbing for quite a few years and MountainProject.com is one of my primary sources for info on routes, areas, conditions, etc. - 'beta' in climber speak. Then I realized that MountainProject has an incredible data set! Thousands of areas, routes, ratings, user contributed info, the list goes on and on. So to get things started, I worked with MountainProject to produce this interactive map showing the number of climbing routes of different types across the US. There is more data in store, so look forward to future visualizations!
To see it in its native environment: www.mountainproject.com/scripts/Factoids