Man that sucks! The only US based manufacturer I have found so far (after a quick search) is Iron Grip: https://irongrip.com/
For barbells, I can only think of these being made in the US now -
Iron Grip
Ivanko (some)
Texas Power Bar
Rogue
Iron Wolfe (these guys were York's high end suppliers)
Kabuki Strength
*York - Maybe the Elite Line, and a few made in Canada as mentioned.
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Plates -
Hi Temp (Bumpers)
Wright Rubber (some Bumpers, marked Wright USA) -
https://wright-equipment.com/ .
Rogue - (some Bumpers, rebranded from the above)
Ivanko - some dumbbells, some of the high end bumpers and powerlifting sets might be, but I doubt it.
Iron Grip - still made here, as mentioned.
York - No, but some bumpers and higher end iron are made in Canada.
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The EPA really put a hurting on plate manufacture from the 70's - onward. Most foundries won't handle weights and such (even expensive specialty runs) because the profit isn't worth the set up and investment anymore

.