Home products made in the USA

Plumbing

• Most Keeney plastic tubular sold at Lowe's is made in the US. It is PVC.
• Home Depot will randomly have Oatey PP tubular at some locations. For whatever reason, it comes in generic-looking packaging with black and white markings instead of normal-looking branded packaging.
• Some PlumbPak plastic tubular (PP) sold on Amazon is made in the US as well, but the product pages can't be relied on for determining this.

Fasteners

• SPAX screws are made in the US or Germany and sold at both HD and Lowe's. Lowe's tends to have lower prices though their boxes don't include the screw bit in them.

Electrical

• Mulberry metal products are generally made in the US. A limited assortment of their white painted wall plates are sold at HD, but beyond that, you'll have to go to a local electric supply store to find them.
• Leviton's 15A "plain" tamper-resistant Decora outlets and midsize nylon wall plates are made in the US. Their website generally has reliable information about country of origin.

HVAC

• Builder's Best for venting solutions. Good luck finding their products anywhere though.
• See Home improvement for some register options (Shoemaker, Continental)