IQ Gaps and pre-school
The average IQ in New Zealand is 103 from what I could google around 100 for the USA
Additionally, as two papers I have delicioused recently show, pre-school matters with IQ. More New Zealanders go to pre-school and while it’s far from proven after all the noise between cause and effect is rather large it does seem to matter. Hence, you could nip part of America’s IQ gap not only with other nations, but with in it itself simply by subdizing early education and providing for free for those under the poverty belt.