The table shows a comparison between the six underground networks in terms of size, age and the amount of people who use these networks each year. It is clear that the three oldest systems are also the biggest, and they serve significantly more passengers than the others.
The underground railway system is the oldest network of the six, which was opened in 1863. It is also the largest network with 394 kilometers of route. While the Paris's network is just about half in size of London's one, it serves more than 300 million passengers per year compared to London's network. Although it is the smallest and the newest system of the three, Tokyo has the biggest number of people using its underground network, at about 1927 million passengers each year.
Despite having the biggest age of the remaining, the system of Washington DC is the biggest with 126 kilometers of route. The number of people used this system is also outstanding with 144 million people compared to just 45 and 50 for Kyoto and Los Angeles respectively. Los Angeles possesses the newest railway system, however, the smallest network belongs to Kyoto.