Is it? I suppose it'll depend on the definition of "third world".
The US ranks ~56th on infant mortality; of the countries that do better, Serbia and Bosnia and Herzegovina are the poorest by far. The IMF classifies both as "developing", and the World Bank calls them upper-middle-income. Even by the Cold War standard, all of them are either First or Second world. The first entry I see that clearly counts, Nauru, is about 40% worse than the US.
Mississippi, though, is ~60% above the national average, with some regions well above that. Which is to say, down around Barbados for infant mortality.
(Of course, I don't mean to imply that "rivaling poor and corrupt developing countries" is something to be proud of. It's just staggering to me how incredibly bad the situation in some parts of the US is.)
The US ranks ~56th on infant mortality; of the countries that do better, Serbia and Bosnia and Herzegovina are the poorest by far. The IMF classifies both as "developing", and the World Bank calls them upper-middle-income. Even by the Cold War standard, all of them are either First or Second world. The first entry I see that clearly counts, Nauru, is about 40% worse than the US.
Mississippi, though, is ~60% above the national average, with some regions well above that. Which is to say, down around Barbados for infant mortality.
(Of course, I don't mean to imply that "rivaling poor and corrupt developing countries" is something to be proud of. It's just staggering to me how incredibly bad the situation in some parts of the US is.)