District officials said the Federal Railroad Administration gave them the green light to start service on Aug. 25. The service runs between the Sonoma County Airport station to the north and San Rafael to the south.
The district had been offering a series of free preview rides on select days since late June while waiting for an audit of its operations by the federal agency to finish.
SMART train rides will be free on the first day of service, which will also feature a grand opening event at 9 a.m. at the Santa Rosa Downtown station at Historic Railroad Square.
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Fares will then be 50 percent off through Labor Day, Sept. 4, and regular fares will be in place on Sept. 5, according to the district.
SMART uses Clipper cards and will run 34 trips each weekday and 10 per day on weekends. Fares start at $3.50 for adults and increase depending on how far a passenger travels, with discounts available for seniors, youth, people with disabilities or those who buy 31-day passes.
"We are proud to say that we are ready to roll," SMART board of directors chairwoman Debora Fudge said in a statement. "Successfully opening a new transit system is a major accomplishment -- and we will remember this day for generations to come."
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"This is truly historic. We want to thank the public for their support, and for providing the North Bay with a state-of-the-art transportation system," board vice chair Kathrin Sears said.
"This system will bring relief to commuters stuck on Highway 101 and provide a stress-free way to travel. It will also provide a major economic boost for both Marin and Sonoma counties," Sears said.
For more information about SMART train service, click here.
Wayne Freedman will have the latest updates on this story starting at 5 p.m. on ABC7 News. Click here to follow his updates on Twitter.