[Symbiote]

I read the first line of the second paragraph ("The original 20.4-kilometre (12.7 mi) system opened in October 2002") and the "System length: 38.2km (23.7mi)" bit from the infobox.

The paragraph you quoted mixes up the situation from before M3/M4 opened with the situation after. I also see where you have taken 13.9km for M1, but on M1's own article page it says 14.3km. Danish Wikipedia gives different figures again.

M1's total length is around 14km, M3 is 15.5km. Christianshavn to the airport is 7km by road, Østerport to Orientkaj about 3km, so the total is roughly 40km.

57 million annual riders on the Washington Metro doesn't seem so much for such a large city. There must be a good chance of getting a seat :-)

Copenhagen's metro claims 107 million annual riders, but the older and more extensive S-train also has 116 million annual riders. Supposedly the total comes to 183 million riders of either/both annually.

[Retric]

Got it, that paragraph is talking about just the M1 and M2 lines even though it starts by mentioning all 4.