Number of operational and under construction subway systems by country. Includes only heavy subway systems or metros.  Subways are defined by The International Association of Public Transport (UITP) as urban passenger transport systems, that are operated on their own right of way, and are segregated from general road and pedestrian traffic. Light rail systems may share roads or have level crossings are not included.

Largest number of subway systems is in China – 46, followed by United States – 16, and India – 15. Total number of countries which have subways is 65. In fifteen more countries subways are under construction. Majority of countries (44) have only one operational or under construction subway system.