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This flight between the two largest cities in the United States is the 20th most popular domestic route in the world, with over 26,000 flights a year. JFK and LAX are among the busiest international airports on their respective coasts, making them gateways for travel in and out of the United States.

The drive between Bengaluru (previously Bangalore) — India’s fifth most populous city and the country’s second fastest growing economy — and India’s capital city of New Delhi is 2,157 miles and can take over 35 hours. A flight between the two, however, can be as short as 2 hours and 30 minutes.

The archipelago nation of Indonesia comprises 17,000 islands. Air travel is a popular way to get from island to island — so popular that the country is home to three of the busiest flight routes in the world. The flight from Jakarta, the capital and largest city, to Makassar, the largest city in eastern Indonesia, is the 18th most popular domestic flight in the world.

Millions of passengers fly between two of the country’s major cities. After all, Beijing is the capital of China as well as its second most populous city, and Shanghai is the largest GDP-contributing city in the nation. Six airlines run over 29,000 flights between the two cities every year.

Shanghai is the most populous and wealthiest city in China, with a huge business district and the nation’s busiest trade port. Flights from Shanghai to Shenzhen, a major technology manufacturing city in the country’s Greater Bay Area, run over 29,000 times a year, making this route the 16th busiest domestic flight route in the world.

The flight from Bogota, Colombia’s capital and largest city, to Medellin, a city whose recent boom in innovation and technology has won it multiple awards, runs over 31,000 times a year. In addition to business travel, increased tourism to the country may account for this route’s popularity. Over 4 million tourists visited Columbia in 2017, a 21% increase from the previous year, according to the United Nations World Tourism Organization (UNWTO).

Over 5.6 million tourists visit Bali each year, with the Denpasar airport being the only one on the island. Because there are not many direct flights to this vacation destination, especially from starting points in Europe, Australia, or the United States, many travelers land in Jakarta first and connect to Bali from there. Six airlines offer service from Jakarta to Bali, running nearly 32,000 flights a year.

Each year, there are over 32,000 flights between Cusco and Lima, Peru. Nearly 10 million people live in Lima, one of the most populous cities in the Americas. Cusco, the starting point for tourists headed to the popular destination Machu Picchu, sees millions of tourists each year.

While driving from Brisbane to Sydney is likely to take 10 hours, the flight is just 1 hour and 30 minutes. Four airlines offer flights between these coastal cities on the east side of Australia, with over 33,000 flights running yearly.

It’s nearly 870 miles by car from Cape Town to Johannesburg, South Africa — a 14 hour drive. With Johannesburg being the largest city in South Africa and Capetown a popular tourist destination — considered one of the world’s most beautiful cities — flights between the two are frequent, carrying 4.7 million passengers yearly, according to FlightSite, an online South African travel agency.

The flight between Saudi Arabia’s two largest cities, Jeddah and Riyadh, runs over 35,000 times a year. The number of passengers taking the flight rose 13.9% from 2016 to 2017, the eighth fastest growing route that year, according to a report by RoutesOnline, a UK-based site about airline news and analysis. The airport in Jeddah is the closest one to the Muslim holy city Mecca, and over 1 million Muslims fly to Jeddah every year to travel to Mecca as part of their holy pilgrimage.

The ninth busiest domestic route in the world, and the busiest route in the United States, doesn’t leave the state of California. There are over 35,000 flights a year between Los Angeles and San Francisco, operated by five airlines. The flight takes about 1 hour and 30 minutes as opposed to 6 hours by car.

Transporting about 5 million passengers in a year, according to Routes Online, the flight between Jakarta, the capital of Indonesia and its largest city, and Surabaya, Indonesia’s second largest port city, is the eighth busiest domestic flight in the world. Tourism has been growing yearly in Indonesia, with 15.8 million foreign tourists arriving in 2018, according to Indonesia’s statistics bureau.

Flights between Sapporo’s New Chitose Airport and Tokyo’s Haneda Airport transported 8.7 million people in 2017, according to Routes Online. The New Chitose Airport is the gateway to Hokkaido Island, a popular tourist destination, known for its volcanoes, hot springs, and skiing. Sapporo attracts about 14 million tourists every year.

Hanoi to Ho Chi Minh City, Vietnam, is the sixth busiest domestic flight route in the world, with three airlines transporting over 6 million passengers every year. One factor is tourism as both cities are popular destinations for foreign and domestic tourists. The number of international tourists in Vietnam tripled from 5 million in 2010 to 15 million in 2018, according to local news reports.

With about 8 million passengers in a year, the trip between Fukuoka and Tokyo’s Haneda airport is the fifth busiest domestic flight in the world. Business travelers may make up a large percentage of passengers because Fukuoka, the most populous city on the Japanese island of Kyushu, is the startup hub of Japan.

Nearly 40,000 flights a year between Sao Paulo/Congonhas Airport and Rio de Janeiro’s Santos Dumont Airport make this route the fourth busiest domestic route in the world. A key business route between Brazil’s top two GDP-contributing cities, the flight takes about 1 hour as opposed to 6 hours by car.

The world’s third busiest domestic flight route is between Mumbai and New Delhi, averaging 130 flights a day, or over 45,000 a year. Of the 10,000 daily passengers that fly between these two cities, about 70% are corporate travelers, according to local media reports. As demand for flights on this route has increased 10% annually and flight capacity at the Mumbai airport is nearly maxed, travelers along this route may see an increase in air fares.

With an average of 148 flights between Melbourne and Sydney daily, this route is the second most popular domestic flight in the world. It is serviced by four airlines. Qantas, the flag carrier of Australia, raked in $854 million from this flight route between April 2017 and March 2018, making it the second most lucrative route in the world for a single airline, according to an OAG report about top revenue routes between 2017 and 2018.

The busiest domestic flight route in the world is in South Korea, operating between Jeju and Seoul’s Gimpo International Airport. With over 200 flights a day and nearly 80,000 annually, this 282-mile flight is serviced by seven airlines. Jeju, a popular resort island with virtually no visa requirements for short visits, is a vacation destination for 15 million tourists every year, and it’s beginning to suffer the consequences.