Until you get caught up in one of those last minute list purges, ostensibly because someone with a similar name registered elsewhere.  You know, the ones that ignored middle names, suffixes (Jr., III, etc.), and the like. The ones that "coincidentally" targeted minority-heavy areas more thoroughly. 
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And then, even if you find out in time to re-register (and they get around processing it in time for the election) you have to enclose a copy of the "acceptable" ID with your first ballot. 
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And for all that, Colorado is better than a whole lot of other States.