Yellowstone National Park will now require visitors 2 years and older to wear face masks in its indoor facilities, citing a rise in COVID-19 cases. Several other parks have similar restrictions, and the National Park Service has implemented a mask mandate on public transit in all of its parks, according to reporting by CBS news.

Of the 10 most-visited national parks of 2021, four now have indoor mask requirements: Yellowstone, the Grand Canyon, Yosemite and the Grand Tetons. All visitors must wear a mask, regardless of their vaccination status.

The National Park Service says masking requirements vary based on the park and its local COVID conditions. If an area is designated as having a high COVID community level by the Centers for Disease Control and Prevention, the park must enact restrictions. The community level is based on the number of hospital beds being used, hospital admissions and the total number of new cases, the CDC says.

To see the complete CBS news report, click here.