This is big news -- the USD below 80!
Various measures showed this sort of thing, repeatedly, in just the last 20 years. The 'index', this DJ Industrial average of non-industrial stocks, skyrocketed during such a period in the mid-1990s (and has not stopped, save for the 'lending correction' called the 'dot-com bust').
The dollar decreases against the yen - US manufacture becomes more competitive. Against the 'euro', etc.
Here's the twist - US manufacture is Red Chinese. But the dollar can increase as quickly as it falls. There's is this range, say with regard to the yen, of roughly 80-100. But in terms of the yuan (or RMB, the 'pepples currency' they call it), the US government actually complained, just a few years ago, that in pegging the yuan to the US dollar, China goods went low when the dollar went low. But if raising the yuan against the dollar also threatens to have foreign investment look to Hong Kong, or directly in Red China where permitted, then it will make things all the more difficult in the US. We'll see.