PORTLAND — Ridership on Amtrak’s Downeaster has topped 500,000 for the first time.

Patricia Quinn of the Northern New England Passenger Rail Authority in Maine says the milestone was reached in the fiscal year that ended June 30. Ridership grew 8 percent, and ticket revenue grew 7 percent. All told, ridership has more than doubled since 2005.

The Portland-to-Boston rail service will celebrate its 10-year anniversary in December. Quinn says 3.5 million passengers have used the passenger rail service.

Last summer, work began on a $35 million track extension to Brunswick. The extension is expected to be completed by the fall of 2012, resulting in another 30,000 to 50,000 riders.