It is under United States military protection and is entitled to federal funding for infrastructure and social programs. Voter turnout was just 23 percent.
Last year, former president Barack Obama signed legislation to address Puerto Rico's fiscal crisis allowing it to file for bankruptcy-like proceedings to relieve its debt.
"The results were quite predictable, as this referendum was actually boycotted by all major parties and organizations, with the exception of the ruling pro-statehood party".
Voters in Puerto Rico approved statehood by nearly 97 percent due in part to a boycott of the referendum by the party supporting a continuation of the current commonwealth status.
On the quaint and narrow streets of old San Juan people were divided over the three options they will face on Sunday's ballot: becoming a US state; remaining a territory; or becoming an independent nation, with or without some continuing political association with the United States.
Ferrer and the PPD believe Puerto Rico is best served by maintaining a voluntary relationship with the U.S.in areas of "mutual benefit", such as economics and defense. This is a tactic that Tennessee used in the 19th century to pressure Congress to admit Tennessee as a state.
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Statehood would allow Puerto Ricans to claim full welfare benefits available to US citizens, but would compel residents to begin paying federal taxes on income obtained on the island.
From the sidelines, Rivera said she refuses to back the man who served 35 years in prison for his involvement with a group responsible for bombings that killed and maimed dozens of people.
The constraints placed on the population by a distant colonial power have had a particularly destructive impact in the last few years when Puerto Rico's lack of economic flexibility has contributed to a devastating financial crisis.
Those who oppose statehood worry the island will lose its cultural identity and warn that Puerto Rico will struggle even more financially because it will be forced to pay millions of dollars in federal taxes. So the statehood party got a little over 500,000 votes.
A majority of the Puerto Rican voters for the first time voted for seeking US statehood back in 2012, when a total of 54% voted in favor.
He argued that Puerto Ricans are "claiming our equal rights as American citizens". Statehood and Rossello lost. The Justice department viewed the language as politically unfair to millions of Puerto Ricans who favor territory status, prompting Rossello to add the territory option. He said he would create a commission to ensure that Congress validate the referendum's results.
If Puerto Rico joined the union, it would be the first state admitted since Hawaii in 1959. Just last week, Rosello signed a law meant to force Congress to act in accordance with the results of the recent referendum. And Congress, the ultimate arbiter of the island's bid for statehood, never picked up the matter.