The first or one of the first Subaru dealerships in the country was at Renton, Washington in the early sixties. Didn't those trade deals in question occur decades after that? 
I drive the interstate a little bit almost everyday. I see the same variety of auto's and trucks here, that I've seen in Alaska and other places I've been in the last ten years. Right now I'm looking out into a FM parking lot and I see the usual mix, not a majority of either one. I think the biggest increase in foreign sales occurred in the late 70's thru the 80's when the quality of American autos took a nose dive. In recent years I've seen a big increase in Ford and Chevy products on the road, while their overall quality gets good reviews from Consumer Reports.