Father Millet Cross

New York

63rd National Monument

.0074 acres

Established by Presidential Proclamation: September 5, 1925 by President Calvin Coolidge

Abolished as a National Monument: September 7, 1949 by the 81st Congress

Wikipedia:

https://en.wikipedia.org/wiki/Father_Millet_Cross

Originally managed by the War Department, the monument was transferred to the National Park Service by President Franklin Roosevelt's Executive Order 6166 on June 10, 1933. It was transferred to the State of New York in 1949 and is now a part of Old Fort Niagara State Park.

According to National Parks Traveler:

When the Army declared Fort Niagara surplus in 1945 (it wasn’t completely demilitarized until 1963), plans were made to abolish the national monument and turn the property over to the state of New York. This was done on September 7, 1949, when Congress transferred the Father Millet Cross National Monument to the state of New York for public use.

How small was it? It was just the cross itself, apparently... "A tennis doubles court is a little over 2,800 square feet, which is nearly nine times the size of the former Father Millet Cross National Monument. "

Pruning the Parks: Father Millet Cross National Monument, 1925-1949, Was the Smallest National Monument Ever Established

National Parks Traveler

https://www.nationalparkstraveler.org/2009/09/pruning-parks-father-millet-cross-national-monument-1925-1949-was-smallest-national-monument-ever-es4482