Jaw
It's OVER 5,000!
It's an interesting map. We don't think of Africa as diverse. But there is an enormous amount of ethnic and linguistic diversity in sub-Saharan Africa. And at the genetic level Africans are much more diverse than the rest of us, who descend from a small group that left Africa 60,000-70,000 years ago. Whenever a small group breaks off like that and becomes genetically isolated, a lot of genetic diversity is lost.
A map that puts the diversity of the US at the level of Middle Eastern countries can be dismissed out of hand. I've had a couple of hundred employees who immigrated to the US from both northern and southern Africa. I don't think any of them would claim that the cultural differences in their countries came close to those of the US. They were universally shocked by things like ethnic food sections in grocery stores. They were also the most racist towards black Americans of any group I've ever encountered. I was forced to fire several for transgressions along those lines.