Daily ridership on the subway system broke a record last month -- five times -- the MTA said Wednesday.

Ridership exceeded 6 million trips on five days in September -- the 10th, 17th, 18th, 19th and 23rd, according to the MTA.

MetroCard swipes topped off at 6,106,694 on the 23rd, a first for the MTA, according to the agency's tally of ridership each year.

This was the fourth year in a row the agency broke a record.

"New Yorkers and visitors alike continue to vote with their feet, recognizing that riding the subway is the most efficient way to get around," MTA chair and CEO Tom Prendergast said in a statement. "This is a phenomenal achievement for a system that carried 3.6 million daily customers just 20 years ago."

The previous record of 5,987,595 was reached last October.

The MTA first started tracking daily ridership in 1985, when there were just over 3.7 million riders.

That was considered low at the time, compared to post-World War II levels, according to the MTA. Passengers at that time transferring to other train systems were counted twice, the MTA notes.

NYC Transit President Carmen Bianco said the gains in ridership reflect a better economy, growing population and subway service that has improved since its low period in the 1980s.

"The trend toward increasing ridership is not expected to slow down," he said.