We can argue whether Sonia Sotomayor, President Obama's nominee to replace retiring Justice David Souter, would be the first Hispanic to serve on the Supreme Court. It's beyond dispute that she would be the first Puerto Rican. Sotomayor was born and raised in the Bronx, but her parents migrated to New York from Puerto Rico, and Sotomayor retains a strong ethnic identification with that Caribbean island. "Our gender and national origins may and will make a difference in our judging," Sotomayor said in a 2001 speech whose mild endorsement of identity politics provoked a ridiculous fuss on the right. A more salient criticism would fault Sotomayor's implied suggestion that her "national origins" are any different from those of, say, Potter Stewart. In the speech, Sotomayor called her parents "immigrants," but the island they departed has been an American territory for 111 years. Why it has remained so longer than any other overseas possession (save the odd atoll or guano deposit) is an enduring historic puzzle.
Puerto Rico is often described as the world's oldest colony, having recently entered its sixth century under off-island rule. Spanish settlers seized Puerto Rico from the Taíno Indians in 1508, a decade and a half after Christopher Columbus "discovered" it. It remained a Spanish colony until the United States chased Spain out of the neighborhood in the Spanish-American War. That was 1898, the same year the United States acquired the Hawaiian Islands. Hawaii became a state. Puerto Rico did not. (Another island acquired in 1898 is Guam, which would share Puerto Rico's 111-year record as a U.S. territory but for its seizure by Japan during World War II.)
Almost from the beginning, the United States was at a loss about what to do with Puerto Rico. An 1899 book by Frederick A. Ober titled Puerto Rico and Its Resourcesrhapsodized about the new colony's ability to provide sugar cane and coffee to the continental United States, which in turn could sell Puerto Rico machinery, flour, cotton, and wool. But Latin America was awash in sugar cane and coffee, and the Puerto Rican population was too poor to provide much of a market for manufactured goods. (The island wouldn't industrialize in any significant way until 1935, when President Roosevelt created the Puerto Rico Reconstruction Administration.) Ober made a more compelling case for the island's military value, "with numerous excellent harbours for the assembling and refitting of our fleets." Various military installations would be built there, but after World War II the island became strategically negligible. Today only one Army base remains.
Over the years Puerto Rican secession movements rose and fell. Most sought independence through peaceful means, but some were violent. In 1950 two members of the Puerto Rican Nationalist Party tried to shoot their way into Blair House to assassinate President Harry Truman, who was staying there while the White House underwent renovation. In 1954 members of the same group managed to wound five members of Congress by firing shots from the House Ladies Gallery while shouting, "Viva Puerto Rico libre." Another group called the FALN (Fuerzas Armadas Liberacion Nacional Puertoriquena) conducted a series of bombings in the United States during the 1970s and 1980s, killing five people and injuring 83. Earlier this month, six Puerto Rican independence advocates staged a nonviolent disruption of House proceedings, shouting and waving signs that said "End the colony." In her Princeton undergraduate thesis in 1976, Sotomayor indicated that she favored secession because the alternatives—statehood or continuation of the commonwealth status established in 1952—would lead to "cultural loss" and continued "Americanization of the island." (A few years later she would write in the Yale Law Journal that if Puerto Rico were granted statehood, it ought to retain mineral rights to its surrounding seabed.)
But the Puerto Rican independence movement failed to gain traction. This was due less to U.S. opposition (for the past half-century the U.S. position on this question has mainly been indifference) than to the risk independence posed to Puerto Ricans' ability to migrate to the mainland, as they started doing en masse in the 1940s. Today, although that migration has slowed, the Puerto Rican diaspora in the continental United States exceeds the island's own population.