Earlier this year, Cambridge quietly accomplished what few cities have dared: through an ambitious zoning reform, it legalized four-story buildings across nearly every neighborhood. The reform dramatically increases the city’s capacity for new housing, with projections that it could add 3,590 net new units by 2040.

This is more than just a housing “win.” It’s a triumph for Cambridge’s unique brand of representative democracy—one that balances citywide priorities with fair representation for diverse communities.

Why did Cambridge succeed where other cities have failed? The answer lies not just in zoning, but in how Cambridge elects its city council.

When cities shift from all at-large councils to district-based council seats, housing construction falls by 21 percent. This is because district- or ward-based council members are strongly motivated to block new development in their neighborhoods. When every member follows that instinct, the city builds less housing.

Traditional electoral systems with all at-large seats can so thoroughly suppress minority representation that they violate the Voting Rights Act. Cities then face a dilemma: Either prioritize citywide interests like housing, or ensure fair representation for localized minority groups. Faced with this tradeoff, many housing advocates have steered clear of debates over electoral design altogether.

Cambridge City Councilor Burhan Azeem, first elected in 2021, campaigned – and won –on a citywide pro-housing platform. When we spoke to Azeem, he said, “In a district-based system, there may not be enough renters in any one district to elect a council member.” In our conversation, he added, “But in an at-large system, renters from across the city can vote for candidates that reflect their priorities.”

This victory was not accidental, but the product of a skilled political entrepreneur and a growing pro-housing movement, empowered by an electoral system that resolves the tradeoff between citywide needs and minority representation.

In a city with district-based representation, the political costs and benefits of development are fundamentally misaligned. The backlash to a new apartment building can be concentrated in a local council member’s district. The benefits are often spread across the entire city or region.

This imbalance creates a legislative norm of deference to the local council member on land-use matters. While the phenomenon has different names in different cities, the outcome is the same: homebuilding stops.

As then-Mayor Ed Koch warned when New York City adopted this model in 1989, it is a recipe for “land use paralysis.” In such systems, only a powerful, independently elected strong mayor can consistently champion citywide interests against the council’s localized concerns.

But Cambridge has a city council-city manager form of government, which vests some of the executive power of a strong mayor system with the council, making the council’s electoral system crucial for enabling citywide coalitions.

Since 1940, Cambridge has elected its city council through an at-large ranked-choice system. Candidates win by reaching a vote threshold—just over 10 percent of ballots—ensuring that any political or demographic group with modest support can earn a seat.

That guarantee of minority representation without resorting to geographic wards is what allows Cambridge to pursue citywide goals like housing.