Somerville, Massachusetts is moving to rebuild sidewalks and plant trees as a single climate project, a pairing that reflects how seriously the city is taking summers that keep getting hotter in a place already built at the edge of what pavement and density can absorb.
With roughly 81,000 residents packed into 4.2 square miles, Somerville is the densest city in New England and one of the densest in the country. That density has a thermal cost: urban heat island conditions push summer temperatures in the city 5 to 10 degrees Fahrenheit above surrounding areas. The problem is sharpest in East Somerville and Winter Hill, lower-income neighborhoods with measurably less tree canopy than wealthier western parts of the city, where heat vulnerability mapping has shown residents face the most risk during heat emergencies.
The city has been losing trees for years. A 2018 canopy assessment found Somerville had shed roughly 15% of its tree cover over the prior decade, losses driven by development pressure, the emerald ash borer and storm damage. The Green Line Extension, Assembly Row and Union Square redevelopment all reshaped the streetscape and cost the city trees in the process. Somerville passed a strengthened Tree Preservation Ordinance in 2020 to slow further losses, but replanting at scale has remained a challenge.
The new project, listed on Massachusetts's procurement portal as the Green and Cool Somerville: Sustainable Sidewalks and Trees Project, bundles sidewalk reconstruction with tree planting rather than treating them as separate jobs. That approach reflects a green infrastructure design philosophy that uses structural soil and larger tree pits to give street trees a better chance of surviving in dense urban conditions, where historically they die within 7 to 15 years. Fixing the sidewalk at the same time also addresses a separate problem: Somerville has faced years of resident complaints and accessibility concerns over cracked and root-heaved walkways, and the city's Vision Zero pedestrian safety commitment has made walkable streets a political priority since 2016.
Federal money has helped make the investment possible. The Inflation Reduction Act of 2022 directed $1.5 billion to the USDA Urban and Community Forestry Program, the largest single federal investment in urban trees in U.S. history, and Massachusetts cities including Somerville have been drawing on those funds.
The contractor selected through this process will shape which streets get rebuilt first and how many trees get planted, decisions that carry real consequences for the neighborhoods already bearing the most heat.
