Complex sentence: Prior to 1959, Hawaii was a territory of the United States in 1945, the United Nations in 1946 listed Hawaii as a non-self-governing territory under the administration of the United States (Resolution 55 (I) of 1946-12-14).
Split into simpler sentences: Prior to 1959, Hawaii was a territory of the United States. In 1945, the United Nations in 1946 listed Hawaii as a non-self-governing territory under the administration of the United States (Resolution 55 (I) of 1946-12-14).