PORTLAND — Amtrak’s Downeaster has set another ridership record, completing its latest fiscal year with 528,292 passengers, the most in its 10-year history, officials said Tuesday.

Ridership figures for the fiscal year that ended June 30 represent the seventh consecutive year of growth for the Portland-to-Boston train service, said the Northern New England Passenger Rail Authority.

Ridership grew 4 percent in the fiscal year, and ticket revenue grew 4.5 percent, the authority said.

The trend coincides with growing national ridership overall for Amtrak, which has set records in eight of the last nine years and in 2011 topped 30 million passengers for the first time.

The rail authority, which operates the Downeaster, says it cannot pinpoint any single factor for the ridership increase. But it says surveys indicate there are more repeat customers.

“The economy comes and goes. Gas prices come and go. But we continue to gain a little bit every year,” Patricia Quinn, the authority’s executive director, said Tuesday. “It shows that more people are getting used to the service and more people are riding it more often.”

The Downeaster makes five daily round-trips between Portland and Boston. Later this year, two of those daily trips will extend north to Freeport and Brunswick.

That will mean even more passengers, with projections for an additional 36,000 riders each year, and another 50,000 passengers when the service expands further, Quinn said.