The number of people visiting public libraries in the UK has dropped by a quarter in the past eight years, according to a government survey.
The proportion of adults using libraries has fallen from 48% to 36% since 2005, according to the Department for Culture, Media and Sport (DCMS).
The drop comes as some councils shut branches in an attempt to save money.
Around 350 libraries are thought to have shut since April or be at risk, according to Public Libraries News.
But cities including Birmingham, Liverpool and Manchester have had major schemes to open or refurbish their central libraries.
The decrease in library visitors has been a relatively steady trend since the DCMS' annual Taking Part survey began in 2005.
The drop has been seen in all parts of the UK and all age groups, the survey found.
The Chartered Institute of Library and Information Professionals (Cilip) said the figures were "deeply disappointing".
Cilip chief executive Annie Mauger pointed out reductions in staff numbers, spending and opening hours that had been felt over the past few years.
"Local authorities have had to make tough choices, but libraries are under pressure and cuts to services will mean that visits drop," she said.
The body, which represents library workers, called for "stronger political leadership that supports a clear national vision to provide high quality, relevant and well used library services in communities across the country".
The figures come days after Cilip passed a vote of no confidence in culture minister Ed Vaizey for his "failures" to intervene on library closures.
In a speech in March, Mr Vaizey insisted libraries were not in crisis, saying: "I'm delighted our library service continues to thrive and modernise."
Referring to the survey results, a DCMS spokesman said libraries were "still hugely important", with 4.5 million visits per week.
"Local authorities, of course, are best placed to decide the scale and nature of the services they provide, based on local needs," he said.
"But it is crucial that they understand what important resources library services are, and adapt and develop services to meet people's expectations in our rapidly changing world.
"There are great examples of innovation and creativity in the delivery of library services, and we want to see more local authorities doing that."
Cllr Flick Rea of the Local Government Association said fewer than 5% of libraries had closed and councils were "working hard to innovate and re-design them" for the future.
"What is clear is that government can't keep reducing funding and expect councils to be able to keep protecting popular library services in this way," Cllr Rea said.
"Any further cuts would certainly result in widespread library service closures and stop this positive work in its tracks."
Other figures from the survey showed that the proportion of adults visiting museums or art galleries had risen from 42% to 53% since 2005.
The East Midlands and north of England have shown the biggest rises in people watching or taking part in the arts, the survey found.
Culture Secretary Maria Miller said the overall figures "show once again just how important the nation's arts and culture are to people".