TUSAYAN, Ariz. (AP) -- Free shuttle service between the Grand Canyon and the neighboring town of Tusayan (TOO'-say-ohn) starts Saturday.The buses will run every 20 minutes from 8 a.m. to 9:30 p.m. through Sept. 5.More than 89,000 people boarded the shuttles last year as a way to cut down on vehicle congestion inside the national park. The more popular South Rim can see up to 10,000 vehicles a day.Visitors can park in four spots in Tusayan to board the shuttles. Those who take advantage of the service will get into the park quicker than other motorists.The service began as a pilot project years ago. The National Park Service says it will continue as funding allows.© 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.