I have 3 farms in Iowa managed for deer, turkey, and upland. Im looking for a property with pure rio grandes to hunt with my bow here soon.
It's a challenge in a number of states to get pure rios because they have stocked a little of both and they don't tend to know the boundaries. There are a pile of merriam-rio hybrids in the western 3/4 of KS and eastern/rio hybrids on the eastern 1/4 of KS.
I've harvested toms with rio colors with what looked like pure merriams standing next to them. I've also harvested merriams in the Front Range mountains in Colo where they are supposed to be pure merriams but had buff tail feathers.
If you want a 100% pure rio you may want to head to a state or area where that's all that is there and it's well inside the boundary of where you would find easterns or merriams.
I've enclosed a map provided by the national turkey foundation of the ranges....the borders are wishy-washy to say the least!