The George Washington University in Washington DC recently became (as far as I know) the second major university in the United States, and the first on the US mainland, to establish a separate Okinawa Collection within the university libraries.
Since its establishment in 2015, the Okinawa Collection has, of course, only continued to grow, under the expert guidance of Japan/Okinawa specialist librarian Mitsuyo Sato. It includes a wide range of materials and resources, both hardcopy and digital, on topics ranging from the history of the pre-annexation Ryukyu Kingdom to more modern political, economic, and social matters.
The Okinawa Collection’s website includes a number of research guides on specific topics or themes within Okinawan Studies, a list of Okinawa-related institutions and organizations around the world, and a page for the Collection’s own news & events.
But the real resource is not the website so much as the Collection itself, if you have the opportunity to visit in person in DC!