Is there a Union label in this? If not, there was probably one in the matching jacket (as Nicole says, there should have been one).
This is a pretty "standard" skirt style, hard to date (for me, anyway), but I'm still going with 70s due to the Antron and Acrylic fiber content and the "made in USA." Could be 80s, too, but I'd guess earlier rather than later. I should really go check some of my 80s sweaters, but from memory, it seems that the acrylic/antron nylon blends were omnipresent in the 70s, and I don't think I saw a lot of it in the 80s, especially with the "Antron" brand name. I think into the 80s, you get a lot of 100% acrylic knits and some "acrylic/nylon," without the Antron name. Can't put my brain's finger on a timeline of any sort, but those DuPont nylons were wildly popular and in everything, it seems, in the 70s, but not as much into the 80s.
Not that this helps much, but if there's a Union label, that would go a long way to solving the mystery!