Gov. Janet Mills signed a bill into law Monday that made Maine the fourth state to ban single-use plastic bags just ahead of Vermont.

Mills, a Democrat, had not previously indicated her position on the Democratic-sponsored legislation.

The Legislature’s House Democratic Office announced the signing. The new law will go into effect on April 22, 2020, Earth Day, to give businesses time to adjust.

The law will go into effect on April 22, 2020. The law exempts certain types of bags, including bags for produce, prescription drugs, newspapers, laundry and live animals.

Maine joined California, Hawaii and New York in prohibiting the use of single-use plastic bags. Vermont followed suit on Monday, becoming the fifth state to ban plastic bags when Gov. Phil Scott signed a bill into law. Several other states, including Delaware and Oregon, are also considering bans.

One of the chief sponsors of Maine’s law, Rep. Holly Stover, D-Boothbay, commended Mills for endorsing L.D. 1532.

“Today, we took an important step towards protecting the wildlife and landscapes that support Maine’s economy,” Stover said in a statement. “With the governor’s signature on this bill, we will be limiting the plastic bags that enter our coastal waters and protecting the health of our marine life.”

Stover’s bill was co-sponsored by Nicole Grohoski, D-Ellsworth, and Rep. Dave McCrea, D-Fairfield. Sponsors said plastic bags have an impact on Maine’s environment and an adverse impact on Maine’s ecosystems.

A total of 24 municipalities in Maine already have instituted local bans on single-use plastic bags. At the request of the Retail Association of Maine and Maine Grocers and Food Producers Association, the new law creates a uniform, statewide policy.

“The grocer and retail community wanted consistency in the policies that govern plastic bags in their industry, and we delivered,” Grohoski said.

The legislation prohibits a retail establishment from using single-use plastic carry-out bags at the point of sale. As an alternative, businesses may offer customers paper bags. But the law requires grocers and retailers to charge a minimum 5-cent fee per bag.

The new law exempts certain types of bags, including bags for produce, prescription drugs, newspapers, laundry and live animals.

“We all need to think twice about what we waste and how that impacts our world,” McCrea said in a statement. “Our future generations deserve nothing less than our best efforts to protect the environment that they will inherit.”

Environment Maine issued a statement praising the governor’s actions.

According to Environment Maine, Americans throw out millions of disposable plastic bags, most of which are never recycled. Plastic has been found in every corner of the planet, from alpine lakes in the Pyrenees to the deepest ocean trenches, and has been ingested by species ranging from humans to sea turtles.

“I’m proud of Gov. Mills and the Maine Legislature for putting wildlife over waste and banning single-use plastic bags,” Carissa Maurin, director of Environment Maine, said in a statement. “Nothing we use for 5 minutes should be allowed to pollute our planet for hundreds of years.”