Legal capacity
Strong evidenceLegalize real projects across enough land and builders respond. Auckland did this at city scale and saw a large permitting boom; narrower reforms have usually delivered less.
Figures from the papers
The strongest post-reform increases appear after roughly five years, especially for large upzonings.
| Years relative to upzoning | All upzonings | Large upzonings | Small upzonings |
|---|---|---|---|
| −4 | -1 | -2 | 0 |
| −3 | 0 | -1 | 0 |
| −2 | -1 | 0 | -1 |
| −1 | 0 | 0 | 0 |
| 0 | 0 | 0 | 0 |
| +1 | 0 | 1 | 0 |
| +2 | 1 | 2 | 1 |
| +3 | 2 | 4 | 1 |
| +4 | 3 | 6 | 2 |
| +5 | 5 | 9 | 3 |
| +6 | 6 | 11 | 4 |
| +7 | 7 | 13 | 5 |
| +8 | 8 | 15 | 5 |
| +9 | 9 | 16 | 6 |
The estimated effects become positive after the reform for both attached and detached homes.
| Years relative to reform | All dwellings | Attached | Detached |
|---|---|---|---|
| −4 | -0.05 | 0 | -0.02 |
| −3 | 0 | -0.02 | 0 |
| −2 | 0.02 | 0 | 0 |
| −1 | 0 | 0 | 0 |
| 0 | 0.1 | 0.05 | 0.04 |
| +1 | 0.25 | 0.15 | 0.1 |
| +2 | 0.45 | 0.3 | 0.15 |
| +3 | 0.75 | 0.55 | 0.2 |
| +4 | 1.15 | 0.85 | 0.28 |
| +5 | 1.45 | 1.05 | 0.35 |
The two groups track similarly before reform and separate gradually afterward.
| Years relative to reform | Less restrictive reform | More restrictive reform |
|---|---|---|
| −5 | 100 | 100 |
| −4 | 100.2 | 100.2 |
| −3 | 100.5 | 100.5 |
| −2 | 100.8 | 100.8 |
| −1 | 101.1 | 101.1 |
| 0 | 101.4 | 101.4 |
| +1 | 102 | 101.8 |
| +2 | 102.8 | 102.3 |
| +3 | 103.6 | 102.9 |
| +4 | 104.7 | 103.5 |
| +5 | 105.6 | 104 |
| +6 | 106.6 | 104.5 |
| +7 | 107.6 | 105 |
| +8 | 108 | 105.4 |
Chicago's cumulative permit paths changed unevenly across neighborhoods and rule types.
| Reform exposure | Affected parcels | Comparison parcels |
|---|---|---|
| Density increase | 410 | 460 |
| Parking reform | 720 | 690 |
| Both changes | 560 | 520 |
Evidence stack
A broad reform covering roughly three quarters of residential land produced a large increase in permitted homes relative to non-upzoned areas.
21,808 additional permitted homes over five years
Keep in mind: Permits are not the same as completed or net new occupied homes.
Study details →Allowing more floor area increased multifamily development activity and availability; the authors' equilibrium model predicts a larger housing stock and lower prices over time.
Modeled long run: 1.9% more housing and 0.5% lower prices citywide
Keep in mind: The price figures are structural simulations, not direct rent estimates, and the reform produced gains and losses for different owners and residents.
Study details →Substantial upzonings increased housing over five to ten years, especially where prior zoning was binding and rents signaled strong demand.
About 9% more living space and housing units in upzoned areas after five to ten years
Keep in mind: Local quality-adjusted rents did not differ significantly from later-upzoned controls; effects may diffuse across the wider market, and the setting is one Swiss canton.
Study details →Loosening reforms were followed by modest average supply gains, while tightening reforms reduced middle-income-affordable units and raised rents.
Loosening was associated with 0.8% more housing after 3–9 years
Keep in mind: Reforms are heterogeneous and the cross-city design remains observational.
Study details →Narrow transit-area upzonings raised affected property values but did not produce detectable additional housing during the five-year study window.
Keep in mind: A localized reform and limited horizon may behave differently from broad reform.
Study details →From evidence to policy