Known Unknowns

A post about some of my known unknowns. It used to be the case that the Republicans were the party of high tarrifs and the Democrats were the party of free trade -- when did that change? And why did it change? The proximate cause is pretty clear, the GOP has always been the party of business, so business changed from wanting protection to wanting to import cheap supplies and move production offshore, but when/why did that happen? Back in the day, the pro-trade argument was a pro-consumer one -- lower tarrifs means cheaper stuff. Nowadays, no one says this in public, instead the official argument is an export-promoting one -- more trade means more exports means more (or better) jobs. When and why did that shift occur? Relatedly, pro-trade policies have shiften from unilateral lowering of barriers (a straightforwardly pro-consumer measure) to multilateral trade agreements which lend export-promotion arguments their viability. Again, when and why?