First of all, this was a typo. We meant to put "American-born" as obviously everyone knows that Meb is an American citizen and won the race in 2014. I fixed the home page.
Second, I think a lot of people don't understand why we use that qualifier from time to time. Most assume that it is because we are racist or that we believe that people born outside of the US are "less American" than those born inside the US. Neither are true. There is no runner I have more respect for than Meb. I myself am an American citizen but I wouldn't have any problem with someone referring to me as "English-born." That is where I was born, why would I be ashamed of that?
Here's the reason we occasionally use "American-born." Have you noticed how over-represented African-born US citizens are in elite distance running? Statistically, African-born citizens make up a small amount of the US population but they comprise a significant percentage of the country's best distance runners. The top three Americans in last year's NYC Marathon were all born in Africa. So was the entire US 10k squad for last year's World Champs. 5 of the 6 guys in the US's 5k/10k Olympic 10k squad in 2016 were born in Africa. The American record holder in the 1500, 3k, 5k, and marathon were all born in Africa.
I don't think this is a coincidence. When it comes to distance running, there does seem to be some advantage to being born and raised at altitude in East Africa. I think most people would accept this.
Now you can point out that someone like Ryan Hall was also born and raised at elevation in California. And it is possible that people born at altitude in the USA are also over-represented in elite running. But I don't know if that's true, and if it is, it is not nearly to the same degree as those born in East Africa.
See where I'm going with this? When we use the "American-born" signifier, we're not trying to be racist. We're trying to provide context.