Houston's economy since the late 20th century has a broad industrial base in energy, manufacturing, aeronautics, and transportation. Leading in healthcare sectors and building oilfield equipment, Houston has the second most Fortune 500 headquarters of any U. S. municipality within its city limits (after New York City). The Port of Houston ranks first in the United States in international waterborne tonnage handled and second in total cargo tonnage handled. Nicknamed the "Space City”, "H-Town", and “the 713”, Houston has become a global city, with strengths in culture, medicine, and research. The city has a population from various ethnic and religious backgrounds and a large and growing international community. Houston is the most diverse metropolitan area in Texas and has been described as the most racially and ethnically diverse major metropolis in the U. S. It is home to many cultural institutions and exhibits, which attract more than 7 million visitors a year to the Museum District. Houston has an active visual and performing arts scene in the Theater District and offers year-round resident companies in all major performing arts.