Starting Wednesday, the U.S. Census Bureau is mailing out paper forms to 65.6 million homes whose residents haven't yet answered the once-a-decade questionnaire. Now the rest of the nation, at least those households that haven't responded, are getting paper questionnaires. About a month into the start of the 2020 census for most U.S. residents, the self-response rate is approaching half of all households, with most responding online.