During his keynote speech at the South by Southwest music festival in Austin, Texas two years ago, Bruce Springsteen reminded his audience of a famous remark made by rock critic Lester Bangs at the time of Elvis Presley's death in 1977: "Lester said that Elvis was probably the last thing we [the worldwide audience for pop music] were going to agree on."

Springsteen was making a point about the diversity of the music being played today, and the consequent splintering of the audience into factions. "There is no key note," he said. "There is no unified theory of everything." He was too modest to point out that the figure closest to undermining Bangs's prophecy is himself, a New Jersey singer, guitarist, songwriter, bandleader and campaigner who turned 64 in September, the week after concluding his latest world tour.

No one else, not even Bob Dylan, combines the role of entertainer with that of social conscience as diligently and effectively as Springsteen, or with such generosity of spirit. During the six months of the Wrecking Ball tour – named after his 2012 album, in which he raged against bankers and their political accomplices – he had played to 3.5 million people at 133 concerts across 26 countries. Fans in Helsinki were regaled with the longest of the many marathon shows he has given over the past 40 years, lasting four hours and six minutes – not including the 30-minute acoustic set he had performed two hours before the scheduled start, for the benefit of early arrivals.

His energy was not spent when the tour finished in Rio de Janeiro. Two weeks later, presumably having got his laundry done, he was turning up with an acoustic guitar at Madison Square Garden in New York to perform at a benefit for Stand Up for Heroes, a charity set up to help injured veterans of the Iraq war. A frequent performer at events held to promote or raise funds for causes he supports, he retains an air of unaffected naturalness and seldom attracts the snide disapproval aimed at some of his contemporaries who are seen as seeking personal publicity for their good works.

His public activism began in 1979 with the No Nukes concert in New York. In 1985 he and Willie Nelson campaigned against the closure of 3M's audio/video tape factory in Freehold, New Jersey. Twenty concerts for Amnesty International in 1988, in cities from Buenos Aires to New Delhi, were followed by a benefit for Sting's Rainforest charity in 1995. He campaigned for John Kerry on the Vote for Change tour during the 2004 US presidential election, appeared at Barack Obama's rallies four years later, and performed at an Autism Speaks fundraiser at Carnegie Hall in 2009. The following year he could be seen on telethons raising money for victims of the Haitian disaster – more than $60m – and Hurricane Sandy. In 2012 he joined the Obama re-election bandwagon. After last year's bomb explosion during the Boston marathon he helped a local punk band, the Dropkick Murphys, to raise funds for the victims.

Two weeks from today, he and the E Street Band will be in Cape Town for the first of 17 dates taking them from South Africa to Australia and New Zealand. This is called the High Hopes tour, named after his new album, to be released tomorrow. As usual, great anticipation surrounds its appearance. His 18th studio album since his debut in 1973 comes at a time when he is expected to produce something that politicians are reluctant or too embarrassed to provide: an honest assessment of the state of things.

"I don't have some big idea," he said in 1996. "I don't feel like I have some enormous political message I'm trying to deliver. I think my work has to come from the inside. I don't start from the outside – 'I have a statement to make, ladies and gentlemen!' – I don't like the soapbox thing, so I begin internally with things that matter to me personally and maybe were a part of me in some fashion."

Nevertheless Wrecking Ball faced that challenge head on, dripping with anger and irony in songs such as We Take Care of Our Own ("From Chicago to New Orleans/ From the muscle to the bone/ From the shotgun shack to the Superdome/ There ain't no help, the cavalry stayed home"); Jack of All Trades ("The banker man grows fat/ The working man grows thin/ It's all happened before/ And it'll happen again"); and American Land ("They tried to get here 100 years ago/ They're still dyin' now/ The hands that built the country/ We're always tryin' to keep out").

His moral compass first came into view on Darkness on the Edge of Town, the 1978 album in which he transformed himself from a celebrant of a semi-mythical neon-lit America of stripped-down hot rods and high-school sweethearts into a kind of pathologist of the American dream, investigating its corroded hulk and examining the lives of the dead and injured. In 1982 a harsh, bare-bones solo album called Nebraska took its tone from Terrence Malick's film Badlands, the story of teenage killers inspired by the Charlie Starkweather murder spree of the 1950s. Two years later he was outraged when the title track of Born in the USA, written in the voice of an embittered Vietnam veteran, was appropriated by the Republican party, who mistook its deceptively exultant chorus and tried to use it as a flag-waving campaign anthem for Ronald Reagan. That sort of misunderstanding, he vowed, would never happen again.

In 1995 he won a Grammy for Streets of Philadelphia, a subdued song written for Jonathan Demme's Philadelphia, the first mainstream Hollywood film to confront the Aids epidemic. In 1996 he gave an interview to the Advocate, an LGBT magazine, in which he endorsed gay marriage, comparing it to his own second wedding, to the singer Patti Scialfa: "It's very different than just living together. First of all, stepping up publicly – which is what you do; you get your licence, you do all the social rituals – is part of your place in society, and in some way part of society's acceptance of you. Those are the threads of society; that's how we all live together in some fashion. There is no reason I can see why gays and lesbians shouldn't get married."

The shooting of the unarmed Amadou Diallo, an immigrant from Guinea, by four NYPD officers inspired his 1999 song American Skin (41 Shots), costing him support among those who had misconstrued his music and taken him for a symbol of beer-drinking, gun-owning all-American manhood. In The Rising, which came a year after 9/11, he made the significant gesture of adding a group of qawwali singers from Pakistan to one song, Worlds Apart. In 2006 he renewed his creative spark and paid homage to the folk hero Pete Seeger by assembling a new band to play traditional folk and protest songs on an album called We Shall Overcome: The Seeger Sessions, a move so successful that the raucous spontaneity and home-made texture of the music was allowed to influence all his subsequent efforts.

High Hopes, assembled from cover versions, songs left off recent albums and new versions of old favourites, appears on the surface to have no central message to impart. But its individual songs, although drawn from a variety of sources, nevertheless convey an impression of a confused America licking its wounds and looking for salvation. Several songs, including a storming remake of The Ghost of Tom Joad, feature Tom Morello, the 49-year-old singer and guitarist formerly with Rage Against the Machine, a political activist whose presence seems to have provided his temporary employer with a burst of fresh energy.

Springsteen loves his job, which is one of the reasons his concerts are such delirious fun, but he is well aware that his chosen milieu, the entertainment business, is "a world of illusions, a world of symbols". Nevertheless his new album finishes with a stirring cover of a great song, Dream Baby Dream, written and recorded 35 years ago by the New York electro-punk band Suicide. Your finest dreams, he is saying, don't have to be illusions. They really can change the world.