Metro lines in China (along with Taiwan and Hong Kong) are being built at an incredible rate. Before 1990, they could be found in just three cities--Beijing, first opening in 1969; Hong Kong in 1979, and Tianjin in 1984.  Growth was modest for many years, but has become exponentially more rapid over time and now dwarfs the rest of the world's progress.  In just the thirty years from 1990 to 2020, the number of cities with a metro system will grow from those original three to over forty--with more to come soon after.

In this time, Beijing and Shanghai in particular have ballooned from nearly nothing into the world's two largest, in both length and annual ridership. The timeline of their expansion alone is mesmerizing.

This is an adaptation of Mini Metros, a project to simplify and shrink 220 of the world's metro and light rail systems. Maps from that project were updated and broken out by year in an attempt to visualize these 30 years of development.

Special thanks to Edward for helping revise the data for each line's opening. If you spot an error, please let me know using the link below.