A new street initiative will temporarily shut down parts of three main thoroughfares to cars and open the spaces to pedestrians this year, Boston Mayor Michelle Wu announced Thursday.

Once a month, between July and September, the city will close a 1- to 2-mile stretch of road between 9 a.m. and 3 p.m., allowing space for walking, outdoor vending and other programs — much like to the city’s six-year-old Open Newbury Street initiative, which shuts down a mile of the Back Bay–area road on a few summer Sundays.

The Boston Open Streets effort is intended to “create and reclaim space for residents” during the warmer months, Wu said, announcing the initiative in one of the target areas on Centre Street in Jamaica Plain. Its closure will take place on Sunday, July 10.

The other two roadway closures will happen along Blue Hill Avenue in Roxbury on Saturday, Aug. 6, and along Dorchester Avenue in Dorchester on Saturday, Sept. 24.

“If nothing else, the past few years have reminded us of precious and important these opportunities are to come together safely, build joy and create connection,” the mayor said.

Wu, who has two small children, added that being near traffic can be “incredibly stressful” to parents.

“It is so freeing when the kids can just scooter down or ride their bikes or run around, and you don’t have to worry about a thing except taking in all the community that’s there,” Wu said.

Administration officials said they selected areas that had strong local business districts along a 1- to 2-mile stretch of road.

Asked how they planned to interact with those upset over the forthcoming closures, officials said advance notice would be critical to the initiative.

“We do close streets on a pretty regular basis in Boston, and the key is just communicating with people,” said Chief of Streets Jascha Franklin-Hodge, adding that “extensive” traffic management plans are being crafted around each closure.

The city is contracting with Shana Bryant Consulting, a Black- and woman-owned small business, to plan and execute the Open Streets program. The $450,000 contract will run through December.

Business owners and community group leaders from Jamaica Plain, Roxbury and Dorchester stood beside Wu and hailed the closures as a long time coming.

“This investment is huge in our community,” said Warren Williams, executive director of the Jamaica Plain nonprofit Three Squares Main Street. “This is about opening the doors so that people can see where businesses are out there and actually patronize them.”

Ed Gaskin, director of Greater Grove Hall Main Streets, added, “Our hope is that this will be an annual investment in community development where parades, festivals and other such events could be celebrated.”

Part of the hopes for the initiative are bringing more business to the local shops on the thoroughfares. Annie Le, board member of Dorchester’s Little Saigon Cultural District, said the effort would draw more spending and activities to the neighborhoods.

“We’re super excited for this,” Le said. “Not every resident in Dorchester can come down to Newbury and enjoy the open streets and the businesses there, so we’re bringing it right to the neighborhood.”

The city will also pilot another initiative called Copley Connect to “study the future use of Dartmouth Street,” the mayor said, which will keep it closed for 10 days straight.

“From Tuesday, June 7th to Friday, June 17th, the block between Copley Square Park and the Boston Public Library will be closed to cars,” Wu added.

Newbury Street, the mayor said, will have extended dates this year, and more details about that specific effort will come later on.