Tourism in Puerto Rico attracted 3.7 million visitors in 2019 and 1.0 million visitors in 2015, a notable increase from the average of 2010–2014 at 3.1 million. Tourism has been a very important source of revenue for Puerto Rico for a number of decades given it is host to diverse natural wonders, cultural and historical buildings, concerts and sporting events. Visitors from the United States do not need a passport to enter Puerto Rico and the ease of travel attracts many tourists from the mainland United States each year.