Despite the low level of participation, Puerto Rican Governor Ricardo Rossello said he would defend the result of the referendum that backed the territory becoming the 51st US state.
Puerto Rico's referendum on statehood delivered a weak turnout Sunday, with almost four-fifths of voters deciding not to cast a ballot, though those who did unanimously backed the territory becoming a US state.
A weak turnout had been predicted, given the call by opposition parties, which supported the status quo, for a boycott of the non-binding vote. Only 23 percent of the island's almost 2.2 million voters took part in the referendum
Despite the low level of participation, Puerto Rican Governor Ricardo Rossello vowed, after casting his vote for full annexation by the United States, to defend internationally the result.
TRT World's Ediz Tiyansan has more from San Juan.
Results showed that 97.2 percent of those who voted wanted statehood, 1.5 percent supported independence and 1.3 percent backed no change.
"We will go before international forums to defend the argument of the importance of Puerto Rico being the first Hispanic state in the United States," Rossello said, appearing with his wife Beatriz Areizaga Garcia in the northeastern city of Guaynabo.
An unincorporated US territory, under American control since 1898, Puerto Rico lacks sovereign powers, an urgent problem at a time when it faces a public debt of $73 billion and its economy has dragged through a century of stagnation.
Rossello, who heads the pro-statehood New Progressive Party, said his government would fight "in Washington and throughout the world" for the Caribbean island territory to be accepted as the 51st US state.
He said Puerto Ricans would gain "all the same opportunities" as other American citizens.
The opposition Popular Democratic Party had said "statehood will win by a landslide" because of the boycott by opposition parties. The Puerto Rican Independence Party had called the vote a "farce."
But the Rossello government insists statehood is the answer to the financial crisis hanging over the island of 3.4 million, where some 45 percent of the population live in poverty.
Puerto Ricans have been US citizens since 1917. But they are not allowed to vote in presidential or congressional elections unless they reside in the mainland US. Sunday's referendum was the fifth on the territory's status, dating back to 1967.