WESTFIELD – One tree at a time, urban centers across Massachusetts are getting greener, as Gov. Charlie Baker celebrated a milestone tree planting on Sept. 23.

Baker and state environmental officials came to Westfield last week to plant the 30,000th tree in the Greening the Gateway Cities program. The dawn redwood tree, at the southern end of General Shepard Park on Broad Street, is one of about 150 trees that the Department of Conservation and Recreation has planted in the downtown area since May.

“This is just a great thing,” said state Sen. John Velis during a tree-planting ceremony on Sept. 23. He said in addition to their environmental benefits, trees are a symbol of vitality and community.

Westfield Mayor Donald Humason Jr. noted that the state’s 26 Gateway Cities — a designation based on below-average incomes and a history as industrial centers — are all older communities, and often lack tree cover in their urban cores. It’s a credit to the state government that it is addressing an imbalance that most people would overlook, he said.

DCR Urban Forester Sarah Greenleaf, who is leading the program in Westfield, said the state’s goal is to reach 2,400 new trees in the downtown area. Her own hope is more ambitious.

“I personally don’t want to stop until 3,000,” she said. “People in the city have been extremely receptive.”

Greenleaf said her crews are booked with tree requests through the end of this year’s planting season. They are now taking requests for spring plantings in 2022.

Residents of the 1,000-acre “canopy zone,” centered on downtown Westfield, can request a tree on private or city-owned property. A DCR forester will visit to determine the best location and best species. There is no cost to the property owner other than a commitment to water the tree for two years.

Though Westfield is far from done, the program is already changing the landscape on certain streets, said Ward 3 City Councilor Bridget Matthews-Kane, who represents part of the canopy zone. She said she remembers there were more trees in the neighborhood when she was growing up, but over the years they died off, and only this program has been able to bring that greenery back. She said she would love to share the benefits of the tree planting program with neighborhoods outside of wards 2 and 3.

“I’m hoping once we plant out the inner ring, we’ll expand it,” she said.

Some of the species of trees being planted in Westfield include dawn redwood, London plane, tulip tree, red oak and river birch. Greenleaf said different species are suited to different types of properties.

“There are only a handful of trees that can go on the tree belt,” Greenleaf said, because of the salt and pollution kicked up by cars.

For more information on what parts of Westfield the program covers, and how to request a tree, visit maurbancanopy.org or call 617-626-1473.

Energy and Environmental Affairs Secretary Kathleen Theoharides said houses next to trees see a 30 percent reduction in energy use and a 20 percent increase in home values, compared with homes in a treeless area. She said the program employs local workers to help with the planting.

“The program has a tremendous success in not only getting trees to communities, but keeping trees alive,” Theoharides added.

In the Pioneer Valley, the program is planting trees in selected urban neighborhoods of Chicopee, Holyoke, Springfield and Westfield. Baker said on Sept. 23 that Greening the Gateway Cities had planted 2,014 trees so far in Holyoke and 2,021 in Chicopee. According to the state website, Springfield has had 1,542 plantings. The program’s leader in number of trees planted is Pittsfield, at 3,072, Baker said.

“We will find a way to find as many trees as our communities will commit” to, he said. “I love planting trees.”

Greenleaf also manages the program in Chicopee and Holyoke. She said Holyoke is getting near its goal of 2,200 trees in the downtown area, while Chicopee is working toward a goal of 2,400 trees in the Willimansett neighborhood. South Willimansett has been particularly responsive, she said.

“We really treed up their neighborhood,” she said.

Both Chicopee and Holyoke have been running their Greening the Gateway Cities program for a few years, she said, and she has noticed the increase in shade cover.