Puerto Ricans are heading to the polls to vote on the status of their Caribbean island in a non-binding referendum.

A former Spanish colony taken over by the United States at the end of the 19th century, Puerto Rico has enjoyed broad political autonomy since 1952 as a commonwealth or "free associated state", but not sovereignty.

As American citizens, Puerto Ricans can freely enter the US and serve in the army.

But they do not have the right to vote for US presidents or elect representatives to congress, even though American politicians have the ultimate say over the territory's affairs.

Voters will have three choices on Sunday - independence, full US statehood or maintaining the territorial standing it has held since 1898.

"The important thing is we allow the people of Puerto Rico to have a choice," Ricardo Rossello, Puerto Rico's young governor, told Al Jazeera.

The Spanish-speaking US territory's referendum proposes "the immediate decolonisation of Puerto Rico", as the island is in crippling $70bn debt.

Rossello, 38, came to power in January on the promise that he would work to end a long "colonial" relationship and make the island the US' 51st state, a move he believes would decrease debt.

"The world has all but eradicated colonial territories, so it is a shameful status in my view. It is one that inhibits the growth of Puerto Rico so it shouldn't move forward," Rossello said.

Only congress, which has yet to approve or review the process, has the power to change the island's status.

A divided island

Puerto Rico has a complicated relationship with the US.

Sunday's referendum the fifth such vote since 1967.

In previous polls, as low as six percent of voters chose the option of independence.

Several Puerto Ricans are boycotting the vote, denouncing the event which will have little impact as a "circus".

"It is invalid and no matter what ends up happening, the US government is not going to approve [the outcome]. It needs to be done a specific way and when it is done the correct way, I will vote," one man told Al Jazeera.

Rossello fast-tracked the referendum process to tackle debt, which currently stands at $70bn [Alvin Baez/Reuters]

Many see the US authority as an intolerable stranglehold, especially considering that President Donald Trump has several times argued against bailing out the distant territory.

Anibal Acevedo Vila, a former governor of Puerto Rico, said he expected a low turnout.

"I can assure you that not even half a million people are going to vote," he told Al Jazeera, adding that the low figure would send a message to congress that the process was invalid.

Debt crisis

Puerto Rico: 179 public schools to close amid financial crisis

Puerto Rico suffers from high social spending and poor infrastructure.

Many young people moving abroad for jobs.

Critics attribute the malaise plaguing the island's economy to Washington's power over them.

For decades, the territory enjoyed a US federal tax exemption that attracted investment by American companies.

But in 2006, congress removed the tax incentive, prompting a pullout which ultimately led to a collapse of the territory's tax base.

Puerto Rico declared the largest ever bankruptcy filed by a local US government in early May after Rossello launched drastic austerity measures, but Washington still has the last word over the territory's finances.

Source: Al Jazeera and news agencies