“I think it is important to note that the economy has been tuned for almost 30 years to be heavily dependent on external trade.”
Are you referring to exports, or imports?
You can’t be referring to exports, as they constitute only about 12% of U.S. GDP.
You could be referring to imports, but even then they are not the lion’s share of U.S. GDP. Imports reached their highest share of U.S. GDP in 2008, at about 17.43% of GDP, and in 2017 stood at 15.03%.
70% or more of the U.S. GDP is within the domestic economy alone.
Now then, your statement MIGHT be better as in a reference to the stock market performance of the biggest U.S. major companies. Their earnings have increasingly reflected their global clout - like Apple’s equipment sold everywhere, GM one of the biggest car makers in China, U.S. agro-industrial-complex feeding the world, Starbucks, McDonalds, Amazon, Walmart - yes. BUT how much of what they sell is produced in America, and how much is produced outside the U.S., and how much of their global sales come back to feed the U.S. domestic economy as investment here. All of that weighs on how much their good result is seen inside the U.S. GDP and U.S. jobs.
The behavior of the big-company-weighted stock market indexes is not necessarily a gauge of how well the U.S. GDP is doing, and vice versa.