Lite mer information (utdraget ur den officiella ESTA-hemsidan):
DO I NEED TO APPLY IF I'M ONLY TRANSITING THE UNITED STATES EN ROUTE TO ANOTHER COUNTRY?
Eligible nationals or citizens of countries that participate in the Visa Waiver Program require either a travel authorization or a visa to transit the United States. If a traveler is only planning to transit through the United States en route to another country, when he or she completes the travel authorization application in ESTA, the traveler should
select "Yes" to the question "Is your travel to the US occurring in transit to another country?".