King County (Seattle’s county) is definitely lagging (hugely) behind the other counties that I have lived in – Oakland County (Oak Park/Southfield/West Bloomfield) and St. Louis County (WashU). Wonder why? Size is one issue (King County is huge), but the participation spread seems to be large enough to have another cause. Mail delivery speed is actually a likely cause as well, of course.
On a related note, Detroit proper is having major problems with the census; it’s not in any of the counties I am comparing below, but I really hope they find a way to get Detroit properly counted so it gets the federal funds it so desperately needs – for a good article, see http://www.freep.com/article/20100324/NEWS05/3240326/1322/Few-in-Hamtramck-Detroit-mail-census-forms. This article got me interested in checking out the participation in general.