mailing census questionnaires to each address on the list, which the householders are to fill out and return by mail;
following up those addresses that fail to report; and
carrying out simultaneously a number of processes designed to assure as complete coverage as possible.
This appendix reviews the basic data collection procedures for the 1990 census, beginning with descriptions by year of the census process for developing the mailing list, collecting the data, and field operations (opening of offices). Subsequent sections describe the 1990 census process for follow-up operations, coverage improvement, local review, and the Post-Enumeration Survey.
Computerized address lists for nearly 60 million housing units (mostly for metropolitan areas) were purchased from commercial vendors. These addresses were assigned to census geography (down to the block level) by using a combination of the automated geocoding capabilities of the TIGER system and clerical geocoding using other sources. The resulting automated address control file then was used to conduct the advance post office check (APOC) by the U.S. Postal Service (USPS), which identified missing addresses and those that needed corrections or were not recognizable for mail delivery.
An address list for another 30 million housing units (mostly in more rural areas) was created by having census enumerators canvass the areas and record the mailing address of each housing unit. This operation was called 1988 prelist. The enumerators also noted the location of each unit on a map (for use in finding the unit later if other visits were needed). These computer-generated maps were one of the first major products of the new TIGER system. The addresses were keyed to form the automated address control file for these areas. That file then was used in 1989 for an advance post office check by the USPS.
For the address control file that was based on the purchased vendor files, the list was updated for APOC changes, and then the addresses were printed out by block (grouped together to form roughly equal-sized workloads, called address register areas [ARAs]). The list for each ARA was assigned to a census enumerator who canvassed each street and building in the ARA looking for (and adding) housing units not on the address list. This operation was called precanvass. Updates to the address list from the precanvass were made, and the resulting