The city plans to spend $8.4 million over the next two years to reimburse the MBTA for the cost of extending its fare-free bus pilot for the three “highest-ridership” routes in Boston, the mayor’s office announced Tuesday.

Mayor Michelle Wu said the city had found the necessary “resources,” by continuing to tap into its American Rescue Plan Act funds, to extend the pilot, which serves three routes in Dorchester, Mattapan and Roxbury, to March 2024.

The two-year pilot was initially set to end in late February, but data from the MBTA and a city analysis conducted last spring pointed to increased ridership on the targeted 23, 28 and 29 routes, cost savings, and steady travel times despite an influx of riders, her office said.

“These have been the highest-ridership routes, they’re key corridors in the city and we’ve seen so many benefits from faster boarding times and more reliability to residents feeling like they have the freedom to go about their daily lives and not have to ration or plan out every single step of all they need,” Wu told reporters after an unrelated press event.

To keep the pilot going, the city plans to use $350,000 from its ARPA funds each month, which over a 24-month period, would cost $8.4 million.

Wu said the city is “very eager” to keep the program going, and continues to talk with other cities across the state and beyond that are testing the same initiative.

“Boston, Merrimack Valley, Worcester and many other communities across the country have demonstrated bold leadership in the face of strong skepticism,” Stacy Thompson, executive director of LivableStreets Alliance, said in a statement. “The success of Boston’s fare-free program is undeniable and we’re thrilled that Boston is extending this program.”

More than half of riders on the three piloted routes in Boston are low-income, the mayor’s office said, pointing to data from the MBTA that show residents in Dorchester, Mattapan and Roxbury are taking advantage of free-free buses.

The city plans to spend $8.4 million over the next two years to reimburse the MBTA for the cost of extending its fare-free bus pilot for the three “highest-ridership” routes in Boston, the mayor’s office announced Tuesday.

Mayor Michelle Wu said the city had found the necessary “resources,” by continuing to tap into its American Rescue Plan Act funds, to extend the pilot, which serves three routes in Dorchester, Mattapan and Roxbury, to March 2024.

The two-year pilot was initially set to end in late February, but data from the MBTA and a city analysis conducted last spring pointed to increased ridership on the targeted 23, 28 and 29 routes, cost savings, and steady travel times despite an influx of riders, her office said.

“These have been the highest-ridership routes, they’re key corridors in the city and we’ve seen so many benefits from faster boarding times and more reliability to residents feeling like they have the freedom to go about their daily lives and not have to ration or plan out every single step of all they need,” Wu told reporters after an unrelated press event.

To keep the pilot going, the city plans to use $350,000 from its ARPA funds each month, which over a 24-month period, would cost $8.4 million.

Wu said the city is “very eager” to keep the program going, and continues to talk with other cities across the state and beyond that are testing the same initiative.

“Boston, Merrimack Valley, Worcester and many other communities across the country have demonstrated bold leadership in the face of strong skepticism,” Stacy Thompson, executive director of LivableStreets Alliance, said in a statement. “The success of Boston’s fare-free program is undeniable and we’re thrilled that Boston is extending this program.”

More than half of riders on the three piloted routes in Boston are low-income, the mayor’s office said, pointing to data from the MBTA that show residents in Dorchester, Mattapan and Roxbury are taking advantage of free-free buses.