What he did with the NYPD scares me a bit but I think overall he was truly responsible for cleaning up that city (physically).  He also implemented the first &quot;Data science&quot; team for a city, which was used to prevent building fires and sewage pipe bursts, among other things [1].<p>[1]: <a href="http:&#x2F;&#x2F;www.nytimes.com&#x2F;2013&#x2F;03&#x2F;24&#x2F;nyregion&#x2F;mayor-bloombergs-geek-squad.html?pagewanted=all&amp;_r=0" rel="nofollow">http:&#x2F;&#x2F;www.nytimes.com&#x2F;2013&#x2F;03&#x2F;24&#x2F;nyregion&#x2F;mayor-bloombergs-...</a>