In 1941, Hawaii had 46 Shinto shrines. Now, there are only 8.
As you might guess from the date, World War II happened: after Pearl Harbor and the Japanese Internment started, Hoover's Custodial Detention List classified organizations in categories:
Priests were classified as A-1.
While not all of Hawaii's Japanese population was interned (this would be a third of the total workforce) the priests were rounded up quickly, and shrines were destroyed. Sometimes the shrines were destroyed by the Japanese themselves who were worried about pressure from the FBI; sometimes the government did it for them.
After my father was released, maybe I think about less than a week the Shinto Shine problem came up. The FBI agents first started talking to my father asking all kinds of questions and left. Then a few days later the FBI (agents) came for the second time, then my father called my brother and me, and told us to take these two men up to see the Kamisama (shrine). So I was so scared so I let my brother take them up there and I was about twenty or thirty feet behind. In the beginning, the FBI started looking around, and all of a sudden one FBI agent picked up a stick and started wrecking the walls outside. The other FBI agent entered inside and scratched everything inside, tore up all the kakejiku (scrolls) and smashed the glass casing and took all the Shinto precious documents with them. My whole family was shocked and scared. This is something that I will never forget.
The shrines were generally not rebuilt; quoting a resident of the Holualoa area, "No one could say anything about the shrine after the war because people would think of you as un-American. So I suppose that after so many years I guess everybody just gave up."
The effects of WWII took a long time to fade; it was only in 1986 when the mainland US got a new Shinto shrine (the Tsubaki Grand Shrine).
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Abe, D. (2013) The Japanese Shinto Shrines in Early Issei: A Case Study in the Kona Coffee Belt Japanese Community. 金城学院大学論集. 社会科学編, 9(2), 48-60.
Abe, D. (2017) Rural Isolation and Dual Cultural Existence: The Japanese-American Kona Coffee Community. Springer.
Kashima. T. (2003) Judgment without Trial: Japanese American Imprisonment during World War II. University of Washington Press.
Nishigaya, L., & Oshiro, E. (2014) Reviving the Lotus: Japanese Buddhism and World War II Internment. In S. Falgout and L. Nishigaya (Eds.), Breaking the Silence: Lessons of Democracy and Social Justice from the World War II Honouliuli Internment and POW Camp in Hawai‘i, vol. 44, (173-198).