That's a pretty big area to be considered a location.
Interaction
No. I don't see any human/environmental interaction in that statement.
not sure Region or Location
Region
Yes, you are correct. Identifying that grasslands covered the Great Plains in the Mid-1800s falls under the category of "Location" in geography. Location refers to where a particular phenomenon or feature is located on Earth's surface. In this case, the grasslands covering the Great Plains describe the specific location of the region during that time period.
