The national average Census mail participation rate is currently at 20%, according to the 2010 Census website, which allows web browsers to track what percent of their town, county and state that has received Census forms have mailed them back so far. According to the map, Montana is currently leading the nation in mail participation rate at 33%, followed closely by Iowa, Wisconsin, South Dakota and Missouri.
In 2000, the mail participation rate was 72%. Starting in May, the Census Bureau will begin door-to-door outreach to collect responses from those households that did not return a form by mail.
Something to chew on: if 100% of households mailed back their forms, taxpayers would save $1.5 BILLION dollars. That's because it costs about $57 to take a Census interview in person, according to Census Director Groves, as opposed to relatively tiny cost associated with mailing out and receiving Census forms via USPS.
img src=US Census Bureau