The number 51k filled with water, representing the drops in a gallon and the lives lost at the Battle of Gettysburg.
The number 2996 filled with a swirling starry night sky, symbolizing both visible stars on a clear night and the lives lost in the 9/11 attacks.
The number 50 mil filled with grains of sand, illustrating both a small pile and the 50 million lives lost during World War II.
The number 73k filled with rice, representing the grains in a 5-pound bag and the casualties during the Normandy campaign.
The number 20 million filled with leaves, symbolizing the leaves on a tree and the deaths during the Taiping Rebellion in China.