Passenger numbers on the Tube have reached a record high - with an average of 3.5 million travellers a day in 2013/14, according to new figures.
London Underground (LU) said 1.265 billion passengers took Tube journeys in 2013/14 - a 3% rise on 2012/13.
Numbers have increased by 33% since 2004, with LU operating an extra 373,000 miles of services in 2013/14 and running more trains that ever.
A transport watchdog said overcrowding was a big concern for commuters.
London TravelWatch said the large rise was unsurprising and more needed to be done to improve journeys.
Chief executive Janet Cooke said: "We know from our research that overcrowding is the major cause of dissatisfaction amongst commuters who use the Underground, so it is essential that Transport for London continue to invest in increasing capacity so that passengers can travel in more comfort."
Since 2004 delays to customers also dropped by 54%, LU said.
LU said asset failures, which include signal problems or track faults, fell to their lowest level in 2013/14.
Mayor of London Boris Johnson said: "Thanks to vital investment and a programme of modernisation we've seen delays cut and more frequent and reliable trains that enable Londoners to get to where they want to go more quickly."