51 States? Puerto Rico Wants in to the United States

Puerto Rico Governor Ricardo Rosselló celebrates after the economically struggling U.S. island territory voted overwhelmingly on Sunday in favor of becoming the 51st state, in San Juan, Puerto Rico, on June 11. On Thursday, Rosselló took his statehood campaign to Washington, D.C. Alvin Baez/Reuters

Puerto Rico Governor Ricardo Rosselló on Thursday asked the U.S. government to recognize the Caribbean island as the 51st state, four days after its residents voted overwhelmingly in favor of being admitted to the union. Congress would have to sign off to make it official.

Related: Will Puerto Rico become the 51st state?

Rosselló, who is part of the New Progressive Party, arrived in Washington, D.C., this week to campaign for statehood. "The U.S. citizens of Puerto Rico have taken a stand and have pleaded a choice," Rosselló said Thursday at the National Press Club in Washington, according to Politico.

Amid a historically low turnout Sunday, Puerto Ricans voted in support of becoming the 51st state. Many of the 97 percent of voters who support statehood believe that such incorporation would revive its economy. The Spanish-speaking island is currently more than $70 billion in debt because of a shift in U.S. corporate tax policy over the course of the past decade. Puerto Rican voters typically show up en masse for electoral events, and have voted previously on statehood in 2012, 1998, 1993 and 1967.

But opposition parties that support either the current territory status of Puerto Rico or its independence boycotted the referendum, and less than a quarter of eligible voters cast ballots. Some have said the process is rigged toward statehood, a notion that Rosselló has refuted.

Rosselló defended low voter turnout. "The will of the people of Puerto Rico is clear," he said, according to video from an NBC News affiliate.

Rep. Nydia Velazquez, the Democrat from New York who is originally from Puerto Rico, called the referendum "political theater" that "is going nowhere," as reported by Politico. Meanwhile, Republican Rep. Don Young said, "It is time that we stop colonizing Puerto Rico." And Democratic Rep. Darren Soto said he intends to respect the voters' support for statehood, and fight for their wishes.

Puerto Rico last month filed for the largest municipal bankruptcy in U.S. history. Its public education system has taken an especially major hit, with plans to shut down about 180 schools.

Under the island's current status as a territory, residents are citizens, but they don't pay certain federal taxes and can't vote in presidential elections. The island is the most highly populated of all U.S. territories.

After the win on Sunday, Rosselló vowed to take the victory to Washington to press Congress to grant statehood to the island. But many are skeptical the U.S. government will accept Puerto Rico as a state and take on more responsibility for the island's economic crisis. The territory appears to be a low priority in the country's capital.

The United States acquired Puerto Rico as a territory from Spain in 1898. Hawaii is the most recent territory to gain statehood, as the 50th, in August 1959.

Crowds turned out on Fifth Avenue in New York City last weekend for the Annual Puerto Rican Day Parade, the same day as the vote on the island.