I think they're doing an all-encompassing locale map like they did in RDR. The locations look varied, as well as the animal life.
The only thing that looks excluded is a Mexico area. So far.
You have some heavy coniferous forested areas, a dry western plains with tall plateaus which are at the base of a large snowy mountain range (the Rockies), you have rich soil plains, and by the looks of it some sort of mining town. There will be a Native American presence, a railroad with what seems to be a late 1880's to late 1890's locomotive, as well as oil fields. Considering oil fields, that's a wide array of areas too. Everyone likes to think Texas and Oklahoma, but they didn't crack into the oil fields into the late 1890s. Colorado in the 1860s, Wyoming in the 1880s. New Mexico? I'm not sure.
I think it's a safe bet we're going to get a wide range along the eastern Rockies states as far as game world.