The Tribute Collection consists of personalized messages and miscellaneous offerings left by visitors to the Memorial on a daily basis, primarily on the anniversary observances of the 2001 and 1993 attacks. The Museum Collections Department reviews the tributes and stores all non-organic materials in a climate-controlled environment.
Some of the tributes are accessioned into the Tribute Collection and designated for potential display. Frequently, the tributes are photographed in situ in order to capture the nature of tribute-leaving practices. The tribute items most often left on the Memorial are photographs, prayer cards, and flowers.