Building kits from US brands and US-based sellers
Amazon ranks by what sells fastest, so a building kit from an established brand gets buried under cheap imports no matter how far you scroll. This page lists the US brands and US-based sellers for building kits, so you can start from the ones worth trusting.
We read each seller's registered country from Amazon's own published seller info. We don't claim anything here is manufactured in the US, only that you're buying from a US brand or a US-based seller.
Confirmed US brands and sellers
6 listings where Amazon's own seller info places the seller in the US. Each badge says which.

Fat Brain Toys Plip Kit, Building Toys for Creative Play, Creative Construction Play Set, Kids Toys Ages 5 to 12

K'NEX - Click & Construct Value Building Set - 522 Pieces, STEM Building, Creative Play Setβ Ages 7+

PicassoTiles 201pc STEM Learning Block Construction Kit with Power Drill and Clickable Ratchet Educational Engineering Toy Set Kids Age 3 Plus Preschool Activity Creative Play with Idea Book PTN201

Playmobil Koala Family Building Kit

Playskool Critter Building Blocks, Toddler and Baby Toy for Ages 6 Months and Up (Amazon Exclusive)

Strictly Briks Building Blocks Starter Kit - Kid Building Toy for Creative Play - Stackable Block Set for Hand-Eye Coordination - Compatible with LEGO & Major Brands Toy Set - 216 Pieces, Basic Colors
US brands we went looking for
More names an AI suggested for this category that we haven't confirmed US on yet. Each badge says how far we've checked it.

Battat Bristle Blocks Basic Builder Box, Interlocking Building Toys

Lincoln Logs 100th Anniversary Tin

MAGNA-TILES Classic 32-Piece Magnetic Construction Set, The Original Magnetic Building Brand

MEGA BLOKS First Builders Deluxe Building Bag Toddler Block Toys Set, Red

Melissa & Doug Wooden Construction Building Set in a Box (48 pcs)

Tinkertoy - Retro Building Set Tin - 85 Pieces
Suggested, not verified. These names came from an AI suggestion, not from our data. We only call a brand US after checking the seller's registered address on its Amazon seller page. Amazon is the seller on these, so its seller page can't tell us who the brand is.