The Fleet Pavilion is a sleek, tented outdoor auditorium overlooking Boston harbour. Like the Millennium Dome, but useful. And actually functioning as a venue. And easy to reach - except, it appears, for our driver, who mistakenly takes us to the Fleet Center, a ghastly concrete sports box being readied for the coming week's rash of Democratic Party fever.
This isn't an isolated political outbreak, of course: Massachusetts is the presidential hopeful John Kerry's seat, with an illustrious history of rebellious liberalism. So Graham Nash may be shrewdly assessing his audience's political leanings when he opens tonight's show with the cheery but pointed greeting: "How'd you like living under martial law?" That wouldn't play well in the Midwest, but here it's greeted with whoops of assent.
It is some indictment of the neutered state of American pop that, even now, Crosby, Stills & Nash remain rock's most vociferous critics of the Bush administration. Them and Linda Ronstadt - a reminder that, despite its indulgent hedonism, the California cokehead-cowboy generation of the early Seventies has retained a sharp political attitude. Tonight, as CSN work through a set liberally sprinkled with peacenik broadsides such as "Military Madness" and "Wooden Ships", and freshly minted protest anthems such as "Don't Dig Here" and "They Want It All", it is clear that their political engagement is a constant thread running through the group's entire career.
The latter song, a punchy number demanding that Enron executives be called to account and confronted by their victims "face to face", receives a standing ovation - a remarkable reception for a song that the audience has never heard before. "The way I see it," quips the rotund, beaming David Crosby as the applause subsides, "if they can bust me, they can bust 'them'!" The middle-aged lady behind me utters an ear-splitting whoop in response, the kind of thing you'd expect from some student jock, not a matronly mum on a rare night out - and she's far from alone in her exuberance, as singalong anthems such as "Love the One You're With" and "For What It's Worth" bring the crowd regularly to its feet.
At one point, a lady alongside me hands me her mobile phone with a request to call her sister Nancy in Pittsburgh, who is 51 today and has asked her sibling to find her a man at tonight's show, as a present. I'm not sure whether to be flattered or insulted. It's different from the Simon & Garfunkel show I attended the week before in Manchester: sure, there are similarly pristine harmonies, and a similarly fiftysomething audience revisiting similarly sunny memories, but the whooping here is in stark contrast to the polite enthusiasm of the British. It's abundantly clear that, for women of a certain age, at least, the three singers have lost little of their outlaw appeal.
The objects of this riotous acclaim are hardly chiselled Adonises, either. Graham Nash is pretty well preserved, but Crosby and Steve Stills are both stout fellows these days, the latter lurching awkwardly about in his Hawaiian shirt as he wrings out another lead guitar break. But the years roll back as the trio cruise through "Carry On", "Déjà Vu", "Marrakesh Express", "Woodstock", and Crosby's freak-flag clarion "Almost Cut My Hair". And despite the frequent splits that have punctuated the supergroup's 35-year career, there's an evident mutual affection that keeps getting them back together, a spirit perhaps best reflected in the chorus of Stills's "Helplessly Hoping": "They are one person, they are too alone, they are three together, they are for each other."