Source: Airlines. Note: Paths are approximate.
The Boeing 747-400, introduced in 1989, made possible ultra-long-range routes like New York / Hong Kong, though often at the cost of a reduced payload. Two airliners, the A340-500 and the Boeing 777-200LR, have made possible even longer routes since their introduction in 2004 and 2005. This marked the end of the dominance of the B747-400 in commercial air services since aircrafts that have better range and are more fuel-efficient became available. The A340-500, which could not effectively compete with the B777, was later discontinued and replaced by the A380-800 in 2007 and the A350 in 2015. Boeing introduced the B787-9 in 2014 to provide a new generation of extreme long-range planes with a better fuel efficiency level and comfort than the B777.
While the longest route is between New York and Singapore, the most prevalent routes link North American cities with Southern China (Hong Kong, Guangzhou, Taipei), using polar routes. The second cluster concerns long-distance flights from North America to the major air hubs of the Middle East (Dubai, Abu Dhabi, Doha). The airlines of these hubs have been very proactive in setting several long-distance services to large cities in Europe and North America to reinforce their connectivity. Since customers prefer direct flights, a greater number of long-distance nonstop flights is emerging as a new generation of long-range fuel-efficient aircrafts become mainstream, such as the B787 (2014) and the A350 (2015). These new aircrafts are particularly relevant since they offer a higher level of comfort for the passengers (higher cabin air pressure and humidity), which makes a big difference over long flights.