The accident happened Friday morning on state Route 9 when the 1915 Ford Model T pulled to the side of the road to allow traffic to pass, the Utah Highway Patrol said. The right front wheel went off the pavement, the wheel's wooden spokes separated, and the vehicle flipped, troopers said.
All four occupants were ejected, troopers said. It was unclear whether the vehicle had seatbelts, although Model T experts say restraints are of little use in the soft-top vehicle that typically travels at no more than 30 mph.
"There's no rollover protection," said Andy Loso, who's part of a Minnesota Model T club but didn't participate in the tour.
Troopers said all four victims were from Minnesota, including the 51-year-old woman who died.
"This club is a family," said Russ Furstnow, a board member of The Model T Ford Club International and chairman of the tour, which involved about 170 vehicles. "We're extremely upset about the whole thing."
Furstnow said the club has never had an accident on one of its tours. The weeklong events take place in different parts of the country each year, with this summer's tour involving drives along the Grand Canyon and in Bryce Canyon National Park.
"The Model T is just a social medium. It brings people together that have a love for these old cars," Furstnow said. "We have these summer reunions and it's almost like an extended family."