Traditional census design allows for late additions to the address list. Although the primary address list building activities occur prior to the enumeration stage, addresses may be added later from the United States Postal Service files, local government updates for new construction, the Local Update of Census Addresses Appeals program, and other operations designed to improve coverage. During the 2010 Census, these types of addresses were added to the list while census enumerations were already occurring in the spring of 2010. Under the original plan for the 2010 Census, which was similar to the Census 2000 design, these late additions would not have received a census questionnaire. Instead, their first chance for a census-initiated enumeration would have been during the Vacant Delete Check operation in July 2010.

In January 2010, the United States Census Bureau Director expressed concerns regarding the workload for the Vacant Delete Check operation. At the time, the Local Update of Census Addresses Appeals universe was approaching 1.8 million cases, a larger than expected workload. The Director was concerned about our plan to enumerate these cases so late in the process and potential respondent recall bias given the enumeration would occur three months after Census Day (April 1, 2010). During that time, the Census Bureau was also heavily promoting mail response through the March to the Mailbox campaign. This caused additional concerns regarding public reactions to the campaign for those respondents who had not yet received a questionnaire to return.

To address these concerns, the Director tasked the Decennial Management Division with developing a plan that would allow for an earlier enumeration of these cases slated for the Vacant Delete Check operation. The Decennial Management Division organized an interdivisional team to explore the options and make a recommendation. On January 29, 2010, with the Director’s approval, the team proceeded to implement the 2010 Census Late Adds Mailout operation. The operation would allow a subset of the “late adds” addresses from the Spring 2010 Delivery Sequence File, the Ungeocoded Resolution operation and the Local Update of Census Addresses Appeals operation the opportunity to receive a questionnaire return in the mail.