Six subspecies of Sandhill Crane have been recognized and they vary in size.
Two subspecies, the Greater Sandhill Crane (Antigone canadensis tabida; breeds in the northern U.S.) and the Lesser Sandhill Crane (Antigone canadensis canadensis; breeds in the Arctic) fly south for the winter.
In their wintering areas, they form flocks over 10,000 individuals.
New Mexico hosts both these subspecies in winter (both in the 3rd photo).
One place this happens is at Bosque del Apache National Wildlife Refuge, 100 mi (160 km) south of Albuquerque, New Mexico.

Bosque Del Apache National Wildlife Reserve, San Antonio, New Mexico, USA, 13 & 14 January 2019

Please check out this video and this video!