From the early concept of Greater Yellowstone that conservationists and scientists pioneered in the 1980s to today, the threads of biological connectivity in the ecosystem, as with elk migrations, have become far better understood. Reese has warned it's essential that citizens rally to protect as much of Greater Yellowstone as possible, particularly when pressures have never been more daunting. Long before this excellent map was created, Reese, a quarter century earlier, has referenced migrations and other transboundary aspects of Greater Yellowstone in his book—see below. Map above created by Wyoming Migration Initiative (migrationinitiative.org). Map below appeared in Reese's book.