The busiest aircraft route in the world is between Seoul, the largest city in South Korea, and Jeju, an island providence of South Korea. Asia hosts most of the world's most popular aircraft routes, but other regions have popular routes as well.
Although Japan has extensive rail infrastructure, the air route between Tokyo and Sapporo is the second-busiest in the world due to the distance between these two major cities. In fact, four of the top 10 busiest travel routes include Tokyo, with connections to Osaka, Fukuoka and Okinawa. Routes between Beijing and Shanghai are popular as well, as are flights connecting Hong Kong and Taipei, two island regions of China.
Flights are popular between Melbourne and Sydney since travel infrastructure is somewhat limited in Australia. In the Americas, only the route between Brazilian cities Rio de Janeiro and Sao Paulo make it to the top 10 list. Still, air travel is popular in the United States, with travelers taking many flights between New York, Chicago and Los Angeles. Growth in the Sun Belt has lead to increased flights through the South. Due to its position as a major travel hub, Atlanta's Hartsfield-Jackson Airport is the busiest in the world as of 2014.