Mapping Cambridge's Rat Hotspots

Rats are so common in Cambridge, they’ve become part of the city's cultural identity, appearing regularly in small talk, art exhibits, and, in neighboring Somerville, even giving a local musical festival its name: Ratchella.

These cultural appearances hint towards an ugly truth: rats are abundant in the city. The Cambridge Day has reported on rats “dripping out of heaters” and construction in Riverside “unleashing [their] fury.” In 2020, the city manager declared what many residents already knew: “We’re still losing the battle” against rats.

Faced with this surge, the city has deployed new tactics, such as installing rat-proof Big Belly trash cans throughout the city, and, as of 2023, deploying SMART box rat traps that use an electrical charge to kill rats and report the number of captures in real time. So, five years later, where does the battle stand? I analyzed 311 reports submitted through Cambridge’s Commonwealth Connect system to identify rat hotspots—and see if the city has made any progress on addressing them.

Here's what I found.

So have these new strategies worked? Using the same 311 data, I calculated the number of rat reports per year since 2016. While rat reports ticked up between 2023 and 2024, overall they have declined from a peak of 1,267 in 2021. As a percentage of total 311 requests, rat reports are down too, declining to 4.4% from a peak of 8.1% in 2021.

More rat mitigation strategies are being tested too. In February, Cambridge and Somerville launched a rodent fertility control study using Evolve, a hormonal product designed to humanely curb rat reproduction over time.

With more than 420 rat reports already submitted in 2025, it’s clear that our struggle with rats is here to stay, but with smarter strategies and sustained, coordinated efforts, the city may finally be on a more hopeful path forward.