The ACS information is mailed to addresses, rather than to individuals, throughout the country. Not including individual names on the address label is one way that we protect the confidentiality of the households that are chosen to participate in our censuses and surveys.
The ACS collects data specific to the housing and people who are living at the address when surveyed. That is, the ACS collects data about the housing characteristics and about the characterisitcs of the people who are currently at a particular address.