Tourism in Puerto Vallarta has increased steadily over the years and makes up for 50% of the city's economic activity. The high season for international tourism in Puerto Vallarta extends from late November through March (or later depending on the timing of the college Spring Break period in the USA.) The city is especially popular with US residents from the western U.S. because of the sheer number of direct flights between Puerto Vallarta and Los Angeles, San Francisco, Seattle, Denver, Phoenix, and Chicago. The city is also popular with tourists from western Canada with a number of direct scheduled and charter flights from western Canadian cities.