A record number of passengers flew on scheduled airline services in 2017: 4.1 billion, according to the International Air Transport Association. Most of all flights are domestic. In fact, the busiest 15 flight routes in the world are all domestic, according to an annual report by OAG, a U.K.-based air travel data company.
Several factors that add to the frequency of domestic flights are geography, a country’s infrastructure, and population size. People living in island countries are more likely to fly between islands; more residents means more traveling, including by air; and flying to one part of the country, if it’s thousands of miles away, is faster than driving.
Vacation travel also plays a role. Some surveys show that people tend to travel within their country when they go on vacations rather than take international trips. Americans follow in that category as well — only about 42% have valid passports, which they need to travel abroad.
The 20 busiest domestic flight routes in the world are in 13 countries on every continent except Antarctica and Europe, and the majority are in the Asia-Pacific region.
To list the 20 most popular domestic flights in the world, 24/7 Wall St. reviewed data from the 2019 OAG Busiest Routes report. The busiest routes are ranked by number of flights for the period between March 2018 and February 2019. Routes are defined as flight paths between specific airports, not cities, so for large cities with multiple airports, only one airport is given in the route. The OAG excluded flights from carries that operate less than 500 flights a year, on any route. Some additional information comes from RoutesOnline, a UK-based aviation network.