I'm kind of confused by something. I just compiled Seattle precinct registered voter counts, versus 18+ Census population. Most of it makes sense, but several wealthy neighborhoods have 100%+ registration rates. One precinct has 426 people over eighteen and 506 registered voters. Another supposedly had 98.8% of its 18+ voters cast a ballot in 2010, which suggests to me that it's not all people who've moved but not been marked inactive. What's going on with that? Is there some reason the Census would the 18+ count would underestimate (not overestimate) eligible voters?
In Washington everyone votes by mail anyway, right? I'd assume that means college students are more likely to still vote at home rather than at school, so it's possibly precincts with a lot of kids who are away from college (and would be counted at college for the census) but vote at home.
