[jjotto]

Meh...

Most discrepancies are rapidly growing Des Moines suburbs, so of course population stats from a couple years ago are going to be inaccurate.

Dallas County Iowa may have 30,000 more people now than it had in 2010, from 66,000 in 2010 to over 90,000 now. These are upscale areas.

[Svartalfiar]

Most discrepancies are rapidly growing Des Moines suburbs, so of course population stats from a couple years ago are going to be inaccurate.

Their numbers are based off a five-year survey, so that's the most they'll be out-of-date. And I would assume that they take into account some kind of population growth based on that number, and not just using it unmodified.

But even if their population numbers are low, those percentages are still rather high. If I remember correctly, about 30% of eligible voters aren't registered, nationwide (I believe this number includes total registrations, which also still includes all those dead/duplicate registrations). So sure, your numbers will vary, but you should expect any given area to have a 70% voter registration rate. Statistically, 100% is an impossibility (outside of a tiny town), as there's always going to be some people that just don't register, or don't want to, or can't. So even a 90% rate would be suspiciously high.