The statement above, from the new book Citizens Without a State, makes an important point. Puerto Rico is not the only territory belonging to the United States, but it is the only large and populous territory. Only two of the other territories have enough people to meet the population standard for statehood set in the 19th century: 60,000.
Some Puerto Rican leaders have claimed that Puerto Rico has a “unique relationship” with the United States. This is not really the case. Puerto Rico is a territory, just like the other territories, but just about 90% of all the people living in U.S. territories live in Puerto Rico. The number has decreased since the census figures shown above were collected, but it’s still just about 3.7 million U.S. citizens. Puerto Rico would not be the smallest state in the union.
Puerto Rico is also the only current territory that has voted for statehood. In 2012, 54% of voters in Puerto Rico said they did not want to continue as a territory, and 61% of those who chose a status option chose statehood. Puerto Rico has not yet petitioned Congress for statehood, but no territory which has done so has ever yet failed to become a state… eventually.
Certainly, every U.S. citizen and national should have equal rights, and every individual is important. But Puerto Rico is the only large concentration of U.S. citizens living in a territory who have already voted for statehood. This makes Puerto Rico unique.