Higher gasoline prices have helped boost the number of bus riders in North Dakota's largest cities.

In Bismarck, Bis-Man Transit Authority Director Robin Werre says ridership is up about 25 percent from last year. She says some of the growth probably is due to gas prices, but some of it may be due to more awareness of the bus services in Bismarck-Mandan.

"We're still a new system, considered new, and so people are still just learning about us," Werre said.

In Fargo, ridership is up 22 percent in January through May this year compared with last year.

Julie Bommelman, the manager of Fargo's Metropolitan Area Transit, said the increase is a pleasant surprise.

"We have added additional service on one of our main routes that runs from downtown Fargo out to West Acres … we've essentially doubled service on that route," Bommelman said.

"We're trying to take all the things into consideration to see what may have contributed (to the increase), but it seems to keep coming back to higher gas prices," Bommelman said.

Grand Forks transportation superintendent Dale Bergman says ridership is up slightly more than 6 percent from last year in his city.

"Mainly, it's because of the price of fuel. They're finding alternative transportation modes," Bergman said.

Minot officials say bus ridership in their city is relatively flat, averaging around 5,000 riders a month.