Ridership on the MAX trains and the bus dipped by 2.7 percent in July compared to the same month in 2016, the second consecutive month of decline after two men were murdered and a third stabbed in a racially charged attack on a MAX train in May.

TriMet leadership blamed the June decrease on fewer attendees at the Rose Festival. But July's continued trend downward could mean something is driving riders away from public transit.

Ridership is down 0.9 percent on the bus and 4.8 percent on the MAX compared to last year.

Trimet spokeswoman Roberta Altstadt says the organization suspects ridership is down because of the unusually hot summer weather, lower gas prices, and possibly because of safety concerns after May's double-homicide.

"It's something we are taking a close look at," Altstadt says. She says the ridership decline could be caused by any or all of these conditions, but TriMet does not have enough information to determine an exact cause.