This dataset gathers a wide range of information about subnational partnerships and collaborations supporting U.S.-Japan Relations. Collected by Prof. Mary Alice Haddad and a team of undergraduate researchers during 2023, it includes information about: 382 sister/friendship cities, 15 sister/friendship state-prefectures, 33 MOUs, 83 City-NGO partnerships/collaborations, 24 Japanese business - US local community collaborations, 15 Japanese consulates in the United States, 100 NGOs promoting US-Japan relations, and US-Japan city partnership data from the Japanese Council of Local Authorities for International Relations.