The world's 14 largest metro systems (photos)

Cairo's Metro system is one of only two comprehensive metro systems in Africa; the other is in Algiers. First opened in 1987, the system consists of three operational lines and today carries about 837 million riders, per 2010/2011 figures. A ride costs just one Egyptian pound, or about US$0.15, which helps to address the city's rapid growth since the 1980s.

Photo: Yusuke Kawasaki

What can you say about Sāo Paulo's famous metro system? Well, for starters, it's the second largest system in South America and the third largest in Latin America, behind systems in Mexico City and Santiago. Launched in 1974, the system now carries 877.2 million people for an average of 3 Brazilian Real, or about US$1.32 -- critical for a city expected to be one of the fastest growing, economically speaking, in the next decade.

Photo: Gustavo Gomes

London's Underground (and its recognizable circular symbol) has reached iconic status, and rightly so: "the Tube" began operation in 1863. Today, it has a breathtaking 11 lines serving almost 1.2 billion passengers, per 2011 figures. A ride isn't cheap, though: the zoned system starts at £4.50, which is about US$6.85. Much cheaper fares can be had through the use of the Oyster contact-less "smart card."

Photo: NeilJS

The Paris Metro system is best known around the world for its original Art Nouveau entrances, which date back to the system's inauguration in 1900. Today's system, which includes 14 inner-city lines and five regional lines, the underground heart of France's capital city, and handles 1.51 billion passengers each year, per 2011 figures. A ride will set you back 1.70 Euro, or about US$2.25.

Photo: Pedro Ribeiro Simoes

Hong Kong's Mass Transit Railway first opened in 1979 and now has 10 light rail lines and a ridership of 1.6 billion, making it the number one mode of public transport in a city of seven million people. How did it achieve such growth in that short amount of time? Government backing. A basic adult fare costs HK$3.50, or about $0.45. Similar to London, Hong Kong's system has a contact-less "smart" fare card named Octopus.

Photo: See-ming Lee

Don't underestimate Mexico City's sprawling Metro, which carried 1.61 billion people in 2012 and spans 12 lines. The system, which began operation in 1969, is what keeps Mexico's capital city moving and is a key strategy to curb the city's massive automotive gridlock problem. At three Mexican pesos, or about US$0.25, a ride won't made too much of a dent in your wallet. It's also music to the ears of a city with 8.8 million people.

Photo: LWY

New York is called the city that never sleeps, and a key tool for that is a transit system that doesn't, either. The 24-hour network carried 1.66 billion people in 2012 -- enough to place it on this list, but also enough to lead the U.S. by a large margin. (Consider: its Lexington Avenue 4-5-6 subway line carries more passengers every day than the entire Chicago, San Francisco, and Washington, D.C. metro systems combined. ) The system has 34 lines and began operation in 1904; a ride will run you US$2.25.

Photo: Derek Key

Guangzhou is probably among the least-known cities on this otherwise star-studded list, but name recognition means little when you successfully carried 1.83 billion riders to their destinations in 2012. The city's metro was the fourth such system built in China, and opened in 1997. The system has grown at break-neck speed since then, and now spans eight lines. It costs as little as two Chinese yuan -- about US$0.33 -- to ride.

Photo: Yeowatzup

Twelve lines. Almost 300 stations. The third-longest system in the world -- and it was only opened in 1993. Oh, and did we mention that there are several more lines under construction? Shanghai's metro saw 2.28 billion passengers in 2012, no slouch for China's most populous city. At just three yuan per ride, or about US$0.50, it's a deal, too.

Photo: Robert Donovan

The oldest metro system in China has hardly rested on its laurels since it first opened in 1969, and now handles upwards of 2.46 billion riders, per 2012 figures. It's the second-longest system in the world. Amazingly, 15 of its 17 lines were built after 2002, and it's still building: two more lines are scheduled to come online in the next two years. With a fare of two Chinese yuan, or about US$0.33, it's a regular contender for most affordable in China, thanks to significant government subsidies.

Photo: Jorge Lascar

Moscow's famed Metro is among the most beautiful in the world, thanks to its marble walls, high ceilings and elaborate chandeliers. But the state-owned system is also a day-to-day powerhouse, with 12 lines and 2.46 billion passengers in 2012. Opened in 1935, the system is rather inexpensive -- just 30 Russian rubles per ride, or about US$0.91 -- and "smart" card-enabled.

Photo: Greg Westfall

It may be a cliché to say, but Seoul's Metropolitan Subway has soul. With 19 lines and a clean, efficient demeanor, there's little reason to wonder why the system saw 2.52 billion passengers in 2011. Seoul's metro first opened in 1974, and as befits its Korean location, it's now kitted out with all the finest technology: mobile applications, massive electronic displays and, naturally, a "smart" payment system that will set you back 1,050 won, or about US$0.93, per ride.

Photo: Keith Lee

The most populous city in the world -- by a long shot -- also has the busiest public transport system in the world, too. Tokyo's joint Metro and Toei Subway systems saw an astounding 3.1 billion riders in 2011. The Metro spans nine lines and the Subway another four; they first opened in 1927 and 1960, respectively. The entire system handles the Japanese and English languages with ease, and contact-less fare cards are plentiful. A ride on the world's most traveled public transit system costs just 160 Japanese yen, or about US$1.61. It's a tremendous human achievement. What have you got to lose?

Photo: Max Talbot-Minkin