“When you play as long as we do, you watch the dancers and you get energized,” Jakobsson said. “It’s a great symbiosis.”

The dance floor is a wonderful equalizer — nobody batted an eyelash when Prime Minister Stefan Lofven, a longtime BAO fan, busted some moves at the concert in the small town of Trosa — and a nod to the tradition of the “folkpark,” where many dansbands plied their trade.

Folkparks, which flourished in the first half of the 20th century, were places where Swedes could dance to live music and enjoy carnival-type attractions. All of Abba’s members played them in the 1960s — Andersson and Ulvaeus even met at one — and they continued in the band’s early days, before switching to arenas worldwide. Nowadays, folkparks can seem old-fashioned, and there aren’t many left.

“The first BAO tour we did, we went to genuine folkparks with dance rotundas and small stages,” Andersson said. “Then we thought we should bring our own folkpark to the people: the dance floor, the games of darts, the hot dogs, the chocolate wheel — a wheel of fortune where you win chocolate. It was too messy so all we kept are the dance floor and the lights. But that’s enough.”