Possible to make JR reservations from USA

We've got a 7 day JR pass and will be traveling from Tokyo to Kyoto on 05May. Since it's Golden Week, can we make reservations to ensure us a spot on the train? If so, can these reservations be made from the USA on line or by phone?

Possible but difficult. In particular, in Japanese only, and requires registration. (For the address and phone number, you can probably enter your hotel's information.) One platform to do it is JR East's eki-net. https://www.eki-net.com/

In any case, Tokyo to Kyoto should not be busy on May 5 (people will be traveling in the other direction), and you can always use unreserved seats.

Oh also you could probably find some JR-affiliated US-based travel agent to do it for you, for a fee. Not worth it really.

You need the pass on your person to make reservations using your pass. You wont have your pass until you arrive and swap your exchange order.

Right, I missed the part about the pass for some reason... Then no, not possible.