All that enthusiasm is probably for naught. In reality, Sunday’s vote didn’t actually signal imminent statehood for Puerto Rico, in spite of the huge margin of victory and insistences from proponents that it would force the issue in Congress. In fact, some observers think the resounding victory of statehood might have actually hurt the long-term prospects of the legislative body finally allowing Puerto Rico fully into the Union. “To make a long story short, the prospects are between zero and negative-10 percent,” says Carlos Iván Gorrín Peralta, a professor at the InterAmerican University of Puerto Rico and a territorial-law scholar.

Although proponents of statehood sometimes cast the referendum as an automatic trigger for congressional review, the facts are that Congress is not bound by any aspect of the referendum vote on Sunday, and that Puerto Rico’s right to self-determination—while an important theoretical international legal concept and germane to its own territorial constitution—simply does not exist in federal legislative terms. Puerto Rico occupies an uncertain political status, one different from the 37 states added to the original 13 United States by Congress.

“All 37 [entry] processes have followed the scheme set out way back in 1787 in the Northwest Ordinance,” says Gorrín. “They were all annexed as part of the United States, designated from that moment to become states eventually.” The landmass of the continental United States, as well as the archipelago of Hawaii and the territory of Alaska, were all added to the U.S. with the legal understanding that they would be eligible to become states, which meant that Congress had clear pathways—including the use of referenda and self-determination—for declaring and granting statehood.

But Puerto Rico and the current U.S. territories have no such future statehood understanding. When Puerto Rico, Guam, and the Philippines were added to the country after the 1898 Treaty of Paris ended the Spanish-American War, their status was as colonial possessions, not as future states. In a series of racialist decisions in the Supreme Court known as the Insular Cases, the Court distinguished the Caribbean possessions as “unincorporated” territories that would first have to be incorporated in order to be eligible for statehood. And that itself would require an express determination from Congress.

If that determination were made at some point in the future, Congress might still abide by a slow process of statehood. “Traditionally, Congress has used three political criteria to decide to finally admit a territory,” says Gorrín. Those three criteria are the number of people in the territory who want statehood, the embrace of “the fundamental values of American democracy” among the territory’s population, and the territory’s solvency.