Why Are South America Flights From The US So Expensive?

International flights to South America from the United States are ridiculously expensive. Especially during the summer travel peak in the Southern Hemisphere (which naturally occurs between early December and late January), the price of traveling from the United States, especially to destinations deep in South America, becomes inexplicably expensive. Destinations like Buenos Aires, Santiago, Rio de Janeiro and São Paulo became some of the most expensive tickets one can get from a major US airport during those months.