The number of journeys being made on Britain's railways has more than doubled over the past two decades, according to official figures.
Data from the Office of Rail and Road (ORR) shows 1.4 billion trips were made by train in 2014/15 compared to just 590 million in 1995/96.
Last year represented a 4.5% increase on the previous 12 months.
Railway historian and author Christian Wolmar said there were many reasons for the increase in journeys, such as improvements in the network, the rise in commuters travelling to work in city centres and more young people preferring to travel by rail rather than car.
He told the Press Association the popularity of rail travel has "taken everybody by surprise" and "nobody quite knows why the numbers are so significantly high".
Mr Wolmar said the number of trains has not kept up with the rise in passengers, leaving the network "stretched".
He added: "On the whole most journeys are okay.
"There are some issues around commuting. Too many people are having to stand and some inter-city trains are very packed.
"But there is no doubt that it's stretched in every which way."
Scotland was the region with the largest annual rise - up 8.7% to 691,000 journeys - and was boosted by Glasgow hosting the Commonwealth Games in the summer of 2014.
The number of journeys within London continued to increase, up 6% to 492.2 million on the previous year.