HOUSTON -

Tens of thousands of American flags were placed at graves in the Houston National Cemetery on Sunday morning, the result of a massive all-volunteer effort to honor each veteran buried there this Memorial Day.

The organization Flags for Fallen Vets brought an estimated 2,500 volunteers together to make it happen.

“This is the only time we get to individually honor each interred vet here at the national cemetery. What we've asked each volunteer to do is – after they've placed the flag – is to recite that service member's name and thank them for their service. We're not truly dead until we're forgotten... so we're going to prevent that and we're going to keep their memory going,” said John Hesse, the executive director of the Houston Flags for Fallen Vets.

Hesse said the organization was founded in the Dallas area three years ago and the goal is eventually place flags at every national cemetery in America.

The flags will remain at Houston National Cemetery until Thursday. Hesse said the organization needs additional volunteers to help collect the flags at 9 a.m. Thursday. For more information, visit the organization's website at www.flagsforfallenvets.com.