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The Zoning Reform Tracker is meant to serve as a hub for documenting zoning reform efforts across the United States. In the first version of the Zoning Reform Tracker, we focus specifically on municipal zoning reform efforts, though we plan to expand this work to account for state reforms within successive updates. It is our belief that anti-density zoning ordinances play a powerful role not only in propagating race- and class-based exclusion, but in shaping life outcomes for children in communities, and therefore, in furthering patterns of negative intergenerational stratification. Restrictive zoning is a powerful mechanism for hoarding resources, with great implications for racial residential segregation, and the former will not fundamentally change without reforming or overriding zoning regulations at the municipal level.

There are two components to the Zoning Reform Tracker: the database, and the webmap. The database is a sortable list of municipalities which each have had some character of a zoning reform initiative, and inclusive therein are columns that describe various components of a given reform initiative. The database is then our most detailed collection or representation of zoning reform efforts across the United States. The webmap, on the other hand, is an interactive national map that marks the points of each reform initiative, and allows the user to explore the question of location, in terms of zoning reform initiatives occurring at the municipal level across the United States. The table below includes the full range of variables captured within the database, while the webmap displays a more focused set of information, which points the user towards the more extensive information contained in the Database. Comprehensively, we believe that this is an important tracker that can not only inform the public, but can also provide support for advocacy efforts across the United States.

The purpose of this page: “Zoning Typology - Reform Type '' is to provide a Reform Type Typology, a classification scheme that describes the classificatory type of a zoning reform effort. The nature of this page in particular, is to allow the viewer to understand the categories we use for the types of zoning reforms efforts that are captured in our tracker; as well as the definition of our reform type typology, its subclass specifications, and how we deploy them in our Zoning Reform Tracker. The Reform Type Typology is meant to describe the what of a zoning reform effort, and/or the political typology of the policy outcome of a zoning reform effort. The subclasses in the typology can be seen below:

Reform Types

  • ADU Reform: Accessory Dwelling Units, Granny Flats, Secondary Units
  • Plex Reform: Duplexes, Triplexes, Fourplexes, 2-4 Unit Multi-family Housing
  • TOD Reform: Transit-Oriented Development, Transit-Specific Density Bonuses 
  • Other Reform: Form-Based Code, Parking Reform, Non-Transit Based Inclusionary Zoning

Justification for Reform Type Typology 

This section is meant to provide a justification, or otherwise an explanation, of our particular reform type subclasses. In this section, we justify our classification, and describe it fully so that viewers can understand it when interacting with the Zoning Reform Tracker. In the first version of the Zoning Reform Tracker, we focus specifically on municipal zoning reform efforts, which is another way of saying that we focus predominantly on city-based reforms; this focus is a consequence of cities primarily bearing control over land-use, zoning and planning decisions for the land within their jurisdiction. At the same time, and on the other hand, counties are another form of municipal reform governance, because they control land-use for Unincorporated areas which are not formally located within the jurisdiction of any incorporated city.1 For the purposes of understanding the first publication of municipal zoning reform efforts in our database and webmap, the majority of reforms are carried out by a city council, with a smaller segment of reforms enacted by a board of supervisors, a board of alders, or a city commission. 

Concerning our definition of reforms, there is a dual-criteria that efforts must meet in order to become incorporated into our tracker: the first item is substantiality, and the second item is distinction. The former item of the criterion is fulfilled if an action institutes substantial change to land-use provisions or the exclusionary basis of single-family zoning, which will ultimately have effects at the municipal level. The latter item of our criterion is fulfilled if a given measure, bill, ordinance, or initiative is marked by either time-based distinction (wherein reforms efforts are separated by months or years), subject-based distinction (wherein reform efforts are distinguished by their reform mechanism or reform type), or by a combination of both.2 On a related note, we have also made separate definitions for reform efforts at both the municipal and state levels of governance, which guide our work. We define a municipal reform as a substantial change in the zoning code or a substantial change in what is known as the general/comprehensive plan of a municipality; with this specific change having implications for reducing the exclusionary basis which has been constitutive of single-family zoning, or general land-use provisions, historically. On the other hand, we define state reform as a substantial change in state policy which has implications for outcomes at the municipal level, and likewise, has specific implications for reducing the exclusionary basis of land-use and single-family zoning. 

In turning towards our Reform Type Typology, we will describe several items: the definition of our reform type typology, its subclass specifications, and how we deploy them in our work. The reform type typology described herein and used in our Zoning Reform Tracker is transferable both to municipal reforms and to state reforms. The reform type classifications were constructed after researching the range of municipal and state-based reform efforts in the United States, and observing the most preeminent examples, the ones that were most popular and repeated most often across the nation in recent years. The viewer may note that there may be some jurisdictions wherein a limited zoning reform policy has been enacted, and that there is a lack of representation of that item within our database and webmap. It is important to remember that we include only substantial reforms, and reforms that are either expansive in their impact, whereby they cover an entire municipality, or reforms that have strong implications for undoing the exclusionary basis of single-family zoning.3   

To continue, our Reform Type Typology is a variable whose purpose is describing the classificatory type of a zoning reform initiative; it is meant to describe the what, and/or the political typology of the policy outcome of a zoning reform effort. In looking at this variable, the viewer should be able to answer the following set of questions: “What kind of change does this zoning reform make? What does this given reform do; will do if it is passed; or fail to do because it was denied?” The typology itself has 4-categories which are reflective of the aforementioned set of questions on the type of a reform effort: 1) ADU Reform, 2) Plex Reform, 3) TOD Reform, and 4) Other Reform. Below we define and specify each subclass in greater detail:

I. ADU Reform

Accessory dwelling unit (ADU) reform is a type of zoning reform wherein a legislative body legalizes the construction of ADUs on single-family zoned areas, or removes restrictions from a prior ADU legalization ordinance. ADUs are often also known by several other monikers (eg. granny flats, secondary units, in-law units, etc.), but in our tracker, we normally keep to the formal language of ADUs to describe this reform type.4 What is an ADU exactly? Accessory dwelling units are small and secondary units on single-family zoned land, with their own kitchen, bathroom(s), and entrances, distinct from the principal dwelling.5 It’s normal for a municipality to have drafted an ordinance initially which legalizes this type of housing in single-family zoned areas, and then follow up from the initial legislation in the years after with one or more ordinances that removes regulations or prohibitions in the approval, owner occupancy and parking requirements, and/or refines the financing or construction process, in order to make construction of ADUs more feasible. When there are multiple successive legislative efforts surrounding ADUs, we usually have chosen to include the ordinances or bills which most significantly alters land-use provision with potential impacts on the exclusionary basis of single-family zoning. This zoning reform type, when enacted in a manner which removes barriers endemic to single-family zoning, effectively allows single-family zoned land to at least minimally increase multi-family density and/or generate less expensive starter home or intergenerational homes.6 An example of an ADU reform that removes barriers and refines the review process of ADU construction, is the state of California, with the string of ADU bills which it has passed in recent years. In particular California has enacted a ministerial-process which automatically approves the building permit for an ADU if it meets certain objective standards; this process circumvents the restrictive homeowner politics that may influence ADUs wherein a discretionary-process characterizes their approval.7 In the latter, in many cases, all neighbors who live within a certain distance from a proposed ADU construction or conversion must be notified about its development, and are essentially granted the ability to delay or defer the development through public hearing proceedings.

II. Plex Reform

Plex reform is a type of zoning reform wherein a legislative body seeks to increase the multi-family housing stock through enabling the construction of small-footprint forms of multi-family housing, particularly on single-family zoned areas. The housing types we group within this classification are: duplexes, triplexes, and fourplexes (as well as the more marginal townhouses and cottage courts). While missing middle housing may be a category that is constituted by at least both ADU and Plex reform, it is noted that many cities wishing to address the zoning reform tend to go about it through a general rezoning method which focuses on allowing duplex to fourplex housing types, the latter mostly granted on the basis of some condition or exception, on prior restricted single-family zoned areas. Many planning scholars note that one way to create opportunity, in the midst of the segmentation of segregated and exclusive higher opportunity neighborhoods, is to have a variety of different housing, at different income levels, in different neighborhoods.8 This kind of zoning reform is then often seen as one of the ways to accomplish this objective. Moreover, this subcategory of zoning reform is noted for its ability to increase neighborhood walkability, housing supply, and diverse types of housing which have different income-entry levels.9 The reform that’s most reflective of this reform type is the City of Minneapolis (MN); both their Minneapolis 2040 Plan which set the stage for changing land-use and single-family zoning drastically in the city, as well as the ordinances which codified the plan into the zoning code, and made up to triplexes developable on what was prior single-family zoned land.10

III. TOD Reform

Transit-oriented development (TOD) reform is a type of zoning reform that uses an incentive structure to create affordable housing development near major transit-stations. In such a policy, developers are given density bonuses or fee reductions––allowances of making larger projects with more units, which therefore make their projects more profitable––contingent, in most cases, on at least a couple of requisites. The first condition is that the project must be constructed within a given distance from a public-transportation nexus, usually within half a mile of a major transit-station. The second condition, an inclusionary zoning provision, mandates that a certain number of the units must be affordable to lower-income households at different levels of HUD’s income limits (moderate, low, very-low, or extremely-low-income).11 TOD approaches are popular because they reduce sprawl, incentivize the use of public-transportation over automobiles, alot a given degree of units and affordable units through inclusionary zoning means, and are therefore a policy that seeks to meet both climate sustainability and housing affordability needs. At the state level, such a policy may take the form of a state encouraging TOD at the level of the municipality by tying the accomplishment of that zoning change to municipal funding; this may be then viewed as a state incentive which seeks to institute a local incentive. At the local level, the reform that’s most reflective of this reform type is the City of Los Angeles’s (CA) Measure JJJ ballot measure.12 This measure seems to have set a strong precedent for other municipalities across the United States who are in progress of General Plan updates, one-off municipal ordinances, or zoning code rewrites.

IV. Other Reform

Other reform is our classification of zoning reform which doesn’t fit into the prior three major types of reform, but is still warranted as an important type which meets the standards of the tracker. The three predominant reforms that make up this reform type are: I) form-based code, II) minimum parking requirement reductions or removals, and III) non-transit based inclusionary zoning. Two examples of this reform type are the City of Cambridge’s (MA) Ordinance No. 2022-5, which removed minimum parking requirements from their zoning code, as well as the City of Grand Rapids’ (MI) zoning code amendment which instituted a form-based code throughout the entirety of the city. A brief note is that, in most cases, we have not included all spot-zoning ordinances at the level of the municipality, or zoning changes which only go into effect for a particular segment of zoning classes, or an overlay which only impacts a limited segment of a municipality. Under our definition, these types of changes would seem to be less substantial than the triad of zoning changes listed above. Though one can argue that TOD is a kind of spot zoning initiative by nature, we would think otherwise: when a TOD policy at the city-wide level is initiated, it extends beyond a given corridor and encompasses the whole city––on the other hand it’s possible to have a more spot oriented overlay of a given corridor which is solely subject to a TOD, which is by nature more limited than a city-wide TOD. Ultimately, this category captures the three subcategories mentioned above, but this typology subclass itself may also encompass reforms not listed or described herein.  

In closing, the aforementioned sections detail the Reform Type Typology which we have used to classify the types or categories of reform efforts recorded in our tracker. In tandem with this documentation, the viewer can look towards our Reform Mechanism Typology which we have used to track the how of zoning reform efforts in the United States. Similarly, the viewer might also look towards our Reform Phase Typology which we have used to track the timeline characteristic of zoning reform efforts. Lastly, we have created a Database Metadata document, which shows information for all of the variables included in our tracker. 

If there are any questions associated with this work, or if you believe that we have missed significant or crucial reform efforts, then let us know through this Google Form, and we may add them to our database and webmap. Other inquiries can be directed to cantong@berkeley.edu

  • 1 See the language used in LAO, “A.G. File No. 2021-016” (California Legislative Analyst’s Office, October 15, 2021), https://lao.ca.gov/BallotAnalysis/Initiative/2021-016; specifically one part of the “Background” section, which reads: “Cities are responsible for local needs, such as planning, to accommodate needed housing, police and fire protection, and local roads. Counties provide similar services in areas outside of cities—unincorporated areas.”
  • 2 We must make a further point about the distinction criterion, particularly as it answers problems and questions related to the granularity of reform efforts included in our tracker. The problem might be framed as such: If a given municipality institutes multiple ordinances for the same type of zoning reform, within days of each other, then wouldn’t representing each granular municipal ordinance as a distinct reform effort serve to oversaturate the tracker for a particular jurisdiction? We address this problem with the distinction criterion. In short form: we include efforts into our tracker not only on the grounds of substantiality, but also on the grounds of distinction. We would then not specify two ordinances which were passed on the same day and over the same type of zoning reform, as two distinct reform initiatives; but we would and do include reforms for a given reform-type which are spread out by months or years, and define these as distinct reform efforts for the purposes of our tracker. It is sometimes the case that a given “reform” is enacted in two municipal ordinances, with one ordinance making most of the change, and the other ordinance instituting a more marginal change. Let us take Gainesville, FL for example. The City of Gainesville made an effort to remove single-family zoning in 2021, and it did so by passing two ordinances on the same day: Ordinance No. 211358, and Ordinance No. 211359. The first replaced single-family zoning with a Neighborhood Residential (NR) zoning category, and specified that up-to plex development would be permitted in this new district; the latter ordinance merely made marginal administrative and language changes to the Land Development Code. As these ordinances were approved on the same day, and were related to the same reform type, we believe that including them both in our tracker (both as rows in our database or as two distinct points on our webmap) would be over-representing Gainesville, which may have the effect of misleading the user, particularly if this same granularity wasn’t pursued in a uniform way across all other jurisdictions in the United States. This kind of oversaturation and granular irregularity would also have the prospective effect of adding error to future computational analyses done with our tracker data. In light of this, we specify the dual-criteria above. At the same time, the distinction criterion does not necessarily mean that we don’t track multiple rounds of reform efforts for a single policy which occur in a given municipality, or likewise, that we don’t track multiple types of reforms which are adopted within a short time-frame in a single municipality. To support this case, we direct the user towards our inclusion of Maplewood, NJ (two ADU reforms separated by a year), and Minneapolis, MN (a Plex reform and Other reform separated by a month). For information on Ordinance No. 211359, which we mentioned above and have not included in our tracker, see City of Gainesville, “File # : 211359” (n.d.), https://gainesville.legistar.com/Legislation Detail.aspx?ID=5711153&GUID=836A2CBB-72EA-4D78-B111-848C15847999&Options=&Search=
  • 3 These definitions are in dialogue with our previous work on single-family zoning in California, the outline on zoning reform established by Karina French in “Decoding Zoning,” and lastly, with our experience researching municipal and state zoning reform efforts across the United States. See Karina French, “Decoding Zoning: Regulation and Reform in California” (Berkeley, CA: Othering & Belonging Institute, May 13, 2021), https://belonging.berkeley.edu/decoding-zoning.
  • 4 California Department of Housing and Community Development, “Accessory Dwelling Units” (n.d.), https://www.hcd.ca.gov/policy-and-research/accessory-dwelling-units#:~:text=ADUs%20have%20been%20known%20by,cottages%2C%20secondary%20units%20and%20more
  • 5 Office of Policy Development and Research, “Accessory Dwelling Units: Case Study” (U.S. Department of Housing and Urban Development, PD&R, June 2008), https://www.huduser.gov/portal/publications/adu.pdf
  • 6 AARP, “The ABCs of ADUs: A guide to ADUs and how they expand housing options for people of all ages” (American Association of Retired Persons, November 2021, 2nd ed.), https://www.aarp.org/livable-communities /housing/info-2019/accessory-dwelling-units-guide-download.html
  • 7 “SB 9: The California HOME Act” (Focus, August 10, 2021), https://focus.senate.ca.gov/sb9
  • 8 MaryJo Webster and Michael Corey, “How Twin City Rules Keep the Metro Segregated” (Star Tribune, August 7, 2021), https://www.startribune.com/how-twin-cities-housing-rules-keep-the-metro-segregated/600081529/?refresh =true
  • 9 Opticos Design, Inc., “The Types” (Missing Middle Housing, n.d.), https://missingmiddlehousing.com/types
  • 10 See the following for the general plan update: City of Minneapolis, “Minneapolis 2040 Executive Summary” (n.d.), https://minneapolis2040.com/media/1447/minneapolis-2040_executive-summary.pdf; and Richard D. Kahlenberg, “How Minneapolis Ended Single-Family Zoning” (The Century Foundation, October 24, 2019), https://tcf.org/content/report/minneapolis-ended-single-family-zoning/; or for two of the most important ordinances which codified the general plan update in the following year, see: Minneapolis, Minn., Ordinance No. 2019-067 (2019), https://library.municode.com/mn/minneapolis/ordinances/code_of_ordinances?nodeId=995793; and Minneapolis, Minn., Ordinance No. 2019-048 (2019), https://library.municode.com/mn/minneapolis/ordinances/ code_of_ordinances?nodeId=990479
  • 11 Federal Transit Administration, “Transit-Oriented Development” (United States Department of Transportation, n.d.), https://www.transit.dot.gov/TOD
  • 12 Elijah Chiland, “Measure JJJ triggers new incentives to encourage affordable housing near transit” (Curbed LA, March 14, 2017), https://la.curbed.com/2017/3/14/14928306/los-angeles-incentives-affordable-housing-transit -jjj#:~:text=Measure%20JJJ%2C%20which%20passed%20with,developers%20building%20near%20transit%20stops