So I hit a rock with the mower...

Assuming "Balance on Current Account" is a flow, not a stock:

Graph #1: Balance on Current Account as a Percent of GDP

The accumulated balance was certainly in our favor until the early 1980s. The U.S. in other words must have had an accumulated surplus until the 1980s. Some minor trade deficits, but no trade debt till later.

On this graph you can't even see much instability arising with the closing of the gold window in 1971.