Probably still number one where its been for over a century. However the share is dropping and using dollar value isn't the best barometer because US goods cost a lot more to produce, and there lies the problem.
Leaving aside the implication that it's a problem that American workers aren't paid what they are in China, the point is that this nonsense about "we don't make anything anymore" is just that. Also, using the share to compare developing economies with developed ones is far more problematic than using dollar values.
(For those curious, the number is 17.7%, and given that the UN stats don't separate mining and utilities from manufacturing, if anything it inflates China's actual production.)