I wouldn't call it the only sourdough library. There is an ongoing effort by scientists to study sourdough, called The Sourdough Project [0]. They are collecting samples from around the country.<p>This is work in progress, but I heard one of the scientists speak recently and he said the idea that starters differ based on location is not showing up in the data. Will be interesting to read updates as they learn more.<p>[0]: <a href="http://robdunnlab.com/projects/sourdough/" rel="nofollow">http://robdunnlab.com/projects/sourdough/</a>