The United States hasn’t added a star to its flag since 1959, when both Alaska and Hawaii entered the fold as the newest states in the union. Now, Puerto Rico is trying once again to become star number 51. This weekend, the territory passed a referendum that will allow the island to seek statehood once more. But as The New York Times’ Frances Robles reports, Puerto Rico’s bid for admission to the union is anything but simple.

Robles calls the referendum “a flawed election most voters sat out.” Though 97 percent of all ballots said yes to statehood, only 23 percent of voters cast ballots—and in Puerto Rico, turnout is often dramatically better. As the Associated Press’ Danica Coto notes, it represents the lowest election turnout on the island since 1967, in part due to boycotts backed by opposition parties.

It’s been 100 years since Puerto Ricans were granted U.S. citizenship with the passage of the Jones-Shafroth Act. Puerto Rico had been occupied by the United States since the Spanish-American war 19 years earlier. The Jones-Shafroth Act gave statutory citizenship to the island’s inhabitants but it does not give them senators or representatives in Congress. Instead, Puerto Rico is given one Resident Commissioner who serves in the House of Representatives without voting privileges. Puerto Ricans do not vote presidential elections, either.

Though Puero Ricans also do not pay federal income tax, the PBS NewsHour’s Omar Etman notes the current economic situation on the island is dire, with nearly half the residents living in poverty and high unemployment. In May, the recession-racked territory sought a form of federal bankruptcy protection for the first time in history.

Puerto Rico has voted on—and passed—statehood before, but Congress did not grant its petition. The Constitution grants Congress the ability to admit new states, but given the low turnout, financial need and political makeup of Puerto Rico, it is unlikely Congress will move forward with admission.

Congress has refused to admit a state before. In 1905, for example, a group of Native American representatives petitioned Congress to admit what was then Indian Territory into the union as the state of Sequoyah. But Congress refused to consider the petition, and Oklahoma was formed instead.

Puerto Rico is likely to meet the same fate—for now. Still, over 517,000 voters participated in the election. And for those who often forget that the island is home to over 3.4 million American citizens, it’s a reminder that the states shown on the flag are only part of the United States’ story.