Answer:
The United States has been made better off by trade. International trade benefits all countries, because the winners are more numerous than the losers.
While it is true that some manufacturing jobs have been lost due to globalization, it is also true that many more jobs have been gained, specially in the service sector, some of them being well better paid than previous manufacturing jobs.
The reason why all countries gain from international trade is that international trade allows each country to specialize in what they do best, something that is known as comparative advantage.