Non-US Citizens need a valid visa to transit through US airports on international connecting flights. Many flights to Costa Rica transit via US airports.
Discussion
Gotcha. Thanks for explaining 🧡
Called an ESTA (can get them in 72 hours). But also paperwork needed for vaccinations. Basically, too much paperwork, and customs queues for a connecting flight for my liking ;-)
If you are transiting and from a non-visa waiver country a person would need a transit visa. https://travel.state.gov/content/travel/en/us-visas/other-visa-categories/transit.html