New Metropolitan Transportation Authority statistics show the city's numbered subway lines are late more often than their lettered counterparts.
Numbered line trains were on schedule 76 percent of the time in September, well below the system-wide average of almost 84 percent.
Transit officials determine if a train is on time if it arrives at the last stop within five minutes of the scheduled time.
MTA officials say the numbered lines are more crowded, leaving them open to more delays because of situations like sick passengers.
The subway line with the best on-time performance rate was the L, with a 96-percent rating.