The Shanghai Metro is the world's longest metro network at 803 kilometres (499 mi) and has the highest annual ridership at 2.83 billion trips. The New York City Subway has the greatest number of stations with 472. As of 2023, the country with the most metro systems is China, with 45 in operation.

Determining the "largest" system depends on whether you measure by track length, number of stations, or annual ridership. As of early 2026, the Beijing Subway holds the title for the world's longest metro network, spanning over 890 kilometers (approx. 550 miles). In terms of the number of stations, the New York City Subway remains the leader with 472 physical stations (or 424 if counting transfers as single units). However, if "largest" refers to the sheer volume of humanity moved, the Shanghai Metro or Tokyo's rail network (including both Metro and JR lines) typically compete for the highest annual ridership, with Tokyo often moving over 3 billion passengers annually. China currently dominates the global rankings for rapid expansion, hosting 11 of the 12 longest metro networks in the world as of this year.