In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.
Q: An archipelago among the Greater Antilles, Puerto Rico includes the main island of Puerto Rico and a number of smaller ones, such as Mona, Culebra, and Vieques. The capital and most populous city is San Juan. Its official languages are Spanish and English, though Spanish predominates. The island's population is approximately 3.4 million. Puerto Rico's history, tropical climate, natural scenery, traditional cuisine, and tax incentives make it a destination for travelers from around the world.
A:
why is puerto rico a part of the us