Puerto Rico’s new governor was sworn in Monday, promising an immediate push for statehood in a territory facing a deep economic crisis. Gov. Ricardo Rossello, 37, proposed several measures aimed at alleviating the crisis shortly after he was sworn in at midnight. Among them is a proposal to hold a referendum that would ask voters whether they prefer statehood or independence. Many have argued that Puerto Rico’s political status has contributed to its decade-long crisis that has prompted more than 200,000 people to flee to the U.S. mainland in recent years. “The United States cannot pretend to be a model...