As far as I'm aware, the non-premium versions of the iPhone (currently, this means the 8, XR and in the near future the 11 - and in the past the 6, 6S, 7 when they became "last-year's iPhone and the SE) are manufactured in Brazil and India - with the main purpose of avoiding incredibly high import taxes on foreign goods in these markets.
Note that they only took these extra steps due to the huge consumer markets in these countries that justify a factory dedicated to supplying only the internal market (200M+ in Brazil, 1.3B+ in India). The absolute cheapest iPhone (including labor+logistics) is still made in China, which is why they take it all the way from Shenzhen to the US instead of importing them from e.g. Brazil.
If for some reason our orange Western leader changes his mind re. China, we might see non-China made iPhones in the US.
Fun fact: India-made iPhones have "Assembled in India" etched on the back. Brazil-made iPhones have "Industria Brasileira"