Four of the Trust Territory districts formed a single federated Micronesian state in 1979, but the districts of Palau and the Marshall Islands declined to participate. Palau, the westernmost cluster of the Caroline Islands, instead opted for independent status in 1978, approved a new constitution and became the Republic of Palau in 1981, and signed a Compact of Free Association with the United States in 1982. After eight referendums and an amendment to the Palauan constitution, the Compact was ratified in 1993 and went into effect on October 1, 1994, marking Palau independent de jure (after Palau was independent de facto since May 25, 1994, when the trusteeship cancelled).