In 2016, the bison received an honor that no American animal ever had before: the title of national mammal. The massive creatures, millions of which once roamed freely across the country, have been fighting the threat of extinction for over a century.

Bison, the largest mammals in North America, were crucial to Native American culture and were found useful by early European settlers in the New World. But after years of reckless hunting and habitat loss, the animals had all but disappeared from the American grasslands by the end of the 19th century.

In one of the world’s first wildlife recovery campaigns, efforts were made to rescue the hundreds that still roamed the land. That marked the beginning of a century-long campaign to increase bison numbers across different terrains. In Ohio—which saw its last wild bison nearly 200 years ago—the 7,000-acre Battelle Derby Metro Park has started an experiment to reintroduce the species to the prairie.

The animals have slowly adapted to the terrain, and the original herd of 6 has nearly doubled. The bison live in two large enclosed pastures in the parkland with a walking trail that runs between, so depending on the location of the bison that day, you can often get a close look at the majestic creatures.