iphones are manufactured in Taiwan and always have been.
Apple developed the technology in California with its staff from many countries. They were first onto the bus with this smartphone which has always been vastly overpriced. A Motorola from Tescos at 65 quid would suit most people just as well as a 1000 pound iphone. Downhill for Apple unless they can pull a new rabbit out of the hat.
The US is top dog in many fields : global finance (basically the New York hub), Hollywood and Disney, Facebook, Google, etc.
But I was talking about production of goods: cars, ships, steel, household appliances, machinery and decent food and so on. The US has fallen behind in an historic trend compared to the Far East and Europe in the above. That is why they have become so protectionist when once they pretended to be in favour of free trade.
However, the USA is pre-eminent in the manufacture of arms, both in terms of making guns for citizens to shoot each other and for sale to foreign countries. The latter is a way to control errant states and force them to due the bidding of Washington. Arms manufacturing keeps a lot of people in jobs, as do the armed forces, but economically they are not a good deal. The crippling cost of maintaining such a huge military/industrial complex has been a major component in the accrual of the National Debt of the USA which is now $22 Trillion.