Puerto Rico is a U.S. territory, not a state, and its residents are American citizens. Though Puerto Rico doesn’t elect members of the electoral college, it does participate in party politics so it does have a say in choosing the nominee.
According to the CNN.COM article Clinton, Obama Court Puerto Rican Voters both candidates were campaigning in different cities on the 24th. Barack Obama was in Bayamon:
… Obama marched along a street in Bayamon, shaking hands with supporters as he walked in front of a banner that said "Puerto Rico Con Obama." This event was referred to as a "caminata," a traditional parade for a candidate. Obama remarked to the crowd, "I will never forget the support and the friendship that I've seen here in Puerto Rico. ... I am absolutely confident that if that we keep on working hard, there's no reason why we can't win here in Puerto Rico, and if we win Puerto Rico, we will win the nomination."
The former first lady may not have understood the language during her first campaign stop in Puerto Rico, but she certainly understood the politics. Before a crowd of a few hundred Puerto Ricans in a muggy high school gym, Clinton pledged to make it a "personal priority" to resolve the statehood issue before the end of her first term. She also vowed to clean up the former Navy testing ranges on Vieques, fund the famous Arecibo radio telescope, use federal dollars to put more cops on the streets and extend tax breaks to Puerto Rican companies. Clinton made each of those promises in English, abandoning a translator early on, despite the growing din among distracted audience members who couldn't understand the full content of her stump speech. Still, enthusiastic supporters hoisted signs like "Puertorriquenos con Hillary" and "Hillary Presidenta" while chants of "Hillary! Hillary!" filled the room.The next day Hillary was in Penuelas, and according to a blog entry on her campaign website:
Hillary clearly understands the needs of the people of Puerto Rico and has amazing proposals to better the island — it is evident that Sen. Clinton really cares. After meeting with many Puerto Rican mayors and discussing the interests of Puerto Rico in Penuelas on Sunday, Senator Clinton stood in front of the audience and openly accepted a debate against Senator Obama on Puerto Rican issues, on Puerto Rican soil. Her exact words were I accept the debate anytime, anywhere.