Connecticut: The Impact of Zoning Regulations on Housing Development
Connecticut: The Impact of Zoning Regulations on Housing Development
A 2023 study (Zoning by a Thousand Cuts by Sara C. Bronin) provides a detailed look at how zoning regulations impact housing development. It reveals that simply changing the number of units allowed is insufficient to spur more housing construction. The research, led by Sara Bronin of Cornell University, involved creating a first-of-its-kind statewide dataset covering Connecticut's 180 land use codes and over 100 housing-related rules across 2,622 zoning districts.
The big idea
Zoning codes contain many regulations beyond unit caps that can constrain housing development, even when more units are allowed. Documenting these "thousand cuts"—including public hearing requirements, minimum lot sizes, maximum height limits, lot coverage rules, parking mandates, and occupancy restrictions—helps identify key reform targets. The study shows how these often-hidden factors combine to limit housing options.
Why it matters
The study exposes the sheer complexity of zoning, with wide variation in rules across jurisdictions that lack policy justifications. Parking requirements prohibit over 100,000 units on land already zoned for multi-family in some cities. Revealing these regulatory constraints empowers policymakers and the public to pursue impactful reforms.
By the numbers:
Connecticut devotes 90.6% of its zoned land to as-of-right single-family housing and just 2.2% to as-of-right multi-family (4+ units) housing. 43 times more land is allowed for single-family than 4+ unit developments.
86.7% of all zoned land allowing housing also imposes minimum parking requirements, averaging nearly 2 spaces per single-family home and apartment even near transit stations. Some towns require 3 spaces per studio.
Over 80% of residential districts have building height limits, capping multi-family buildings at 3-4 stories on average (median 3.5 stories for buildings allowed as-of-right).
Minimum lot size requirements cover 94% of land allowing single-family housing as-of-right, with over half of that land having 2+ acre minimums. Large lot rules are less prevalent for multi-family.
Occupancy restrictions apply to 79% of land allowing accessory dwelling units (ADUs), with owner-occupancy rules on 70% of ADU land being the most common. 25% of ADU land requires occupants to be family or employees of the owner.
How they did it
The researchers exhaustively cataloged Connecticut's zoning codes at the district level, using a methodology that improves on prior zoning research prone to unreliable surveys or incomplete analyses focused on just a few metrics. Combining spatial and textual analysis, they harmonized data statewide, engaged local planners for feedback, and created an interactive online map.
What's next
The Connecticut Zoning Atlas provides a model for a new National Zoning Atlas aiming to map zoning regulations nationwide. Using the Connecticut methodology, over 50 institutions are already collecting data across 21 states. Machine learning and new data standards will accelerate the effort to help drive evidence-based policy.
Bottomline
Ending single-family zoning is just a start. Parking mandates, height limits, minimum lot sizes, public hearing requirements, and occupancy restrictions kill housing by a "thousand cuts." Systematically mapping these barriers can inform comprehensive reforms to boost affordability, economic opportunity, and racial equity. With a national zoning atlas, we can catalyze research and policy to improve the places we call home.