This page contains information on the efforts to maintain two decades of political notes. This includes ensuring, when possible, that the tens of thousands of links point to either the intended page, an archive of the page, or a suitable replacement.
I extract all links from a pol note page and get the http status code for each, following redirects if necessary. I identify broken links as having 4** codes, and also visually scan the redirects to identify missing pages, e.g. when it redirects to the home page. Links that don't meet these criteria, but nevertheless no longer provide the intended text, would remain unfixed.
Here are the number and fraction of links per year of pol notes that were found to be broken as of early 2018 and have been fixed: