Boston is banning single-use plastic bags in the city's stores.
Democratic Mayor Marty Walsh said Sunday he has signed the ordinance because of the environmental benefits, such as reducing litter.
He says he's still concerned about the impact on low-income residents and seniors.
It goes into effect next fall.
The City Council unanimously approved the ordinance last month.
It bans flimsy plastic bags and requires businesses to charge no less than 5 cents for other checkout bags, including reusable bags, compostable plastic bags and paper bags with handles.
Paper bags without handles would still be free. Businesses would keep all bag fee proceeds.
Fifty-nine communities statewide impose fees or limits on plastic bags.
Some Rhode Island communities have banned single-use plastic shopping bags.