Story highlights Friday is POW/MIA Recognition Day

Items left at the Vietnam Memorial are kept by the NPS

More than 1600 Americans are still missing from the Vietnam War

(CNN) Friday marks POW/MIA Recognition Day, meant to mark the sacrifice made by American prisoners of war and those still missing in action.

One of the places where American prisoners and missing are commemorated year-round is at the Vietnam Veterans Memorial in Washington, where since the memorial was dedicated in 1982, visitors have left tokens in memory of the fallen, the imprisoned and the missing.

But what happens to those items after visitors leave?

The wall is under the care of the National Park Service, and NPS staff has collected and archived the majority of items left there. And though there are a number of other memorials on the National Mall, the NPS only regularly collects items left at the Vietnam Memorial.

"We weren't sure what to do with the items at first. There were a couple of maintenance people who felt too guilty to throw away the things that they were finding there, and so they kind of squirreled away the items and kept them," NPS Museum Technician Janet Donlin told CNN. "And in 1984, our regional curator found out that this was happening and she decided to make it an official Park Service collection."

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