When the media and some urbanists say more people live in cities than ever before, they're giving unspoken credit to megaregions—conglomerations of urban and suburban areas, where one metropolitan area blends into another, and potentially more. According to most counts, there are at least 12 megaregions in the United States, and the quick growth of these massive and diverse conglomerations requires new approaches to the planning and design of the built environment. A book published today and titled Designing the Megaregion: Meeting Urban Challenges at a New Scale, by professor emeritus and author Jonathan Barnett, charts a course toward sustainable megaregions.

Planetizen presents the following excerpts, reprinted with permission, explaining the connections between the development regulations and zoning codes of local planning to the environmental, economic, and social outcomes of megaregions. The excerpts serve as yet another example of the immense power of local planning decisions to exceed the boundaries of local planning jurisdictions, and the need to reform local development regulations with growth at the scale of the megaregion in mind.

Rewriting Local Regulations to Promote Sustainability and Equity

Local regulations control the physical shape and structure of cities, suburbs, and towns by determining how, when, and where real estate development occurs, and defining the legal rights of property owners. These regulations also have a huge effect on the natural environment, on whether or not an area can have the densities needed to support transit, and in many places, development regulations have been a way to institutionalize discrimination. While states and multistate compacts now have the ability to set detailed policies for growth management, implementation of these policies will largely be through development regulations written and administered by local governments.

Zoning and subdivision, the principal components of local development regulations, originated in the United States in the 1920s. Most local governments amended their regulations in the 1960s in response to new concepts favored by influential law and planning schools. Rules were changed to control the size of buildings by a ratio of permitted space to the size of the lot, in addition to the height limits and setbacks from the edge of the property that had been the basic controls before.

Zoning maps were amended to make more distinctions among different types of real estate development; and subdivision standards—which regulate street designs and lot sizes in new developments—became much more detailed and precise. At the same time that the rules became stricter and more complicated, a procedure called planned unit development (PUD) was added that permitted local authorities to make exceptions to some of the rules for larger properties on the basis of an actual development plan.

Two generations later, almost all zoning and subdivision regulations are now out of date. They do not relate well to the current real estate market, to the development needs created by population growth in the megaregions around the country, to an economy changing rapidly in response to advances in telecommunication and transportation networks, and to changes in climate that, over time, will alter the natural environment in which development takes place.

Many people have concluded that managing development at the scale of the megaregions is impossible, particularly because zoning and sub-division regulations are adopted and administered by cities and towns, and sometimes counties, and there are hundreds of these local governments in every megaregion—each with its own political and economic concerns. But as we have seen, states have the power to set the frame-work for development regulations, and advanced geographic information systems now give states an objective basis to do this.

Development regulations have the potential to help solve the megaregions’ pressing growth-management and environmental problems. While every local set of regulations is different, they contain many similarities because they are based on widely shared templates. Revising only a few critical aspects of zoning and subdivision will go a long way toward addressing the biggest impediments to designing the megaregion, without disturbing the way other parts of the regulatory system affect most of the land area of cities, towns, and suburbs. The changes are relatively simple to enact. Most jurisdictions could make the necessary changes on their own, and the changes could also be mandated by state governments through their enabling legislation.

Supporting Both Equity and Transportation by Mixing Land Uses and Housing Types

The rezoning and remapping of commercial corridors to permit multifamily housing and row houses provides a way to reuse retail properties that are becoming obsolete because of e-commerce.

Rezoning commercial corridors can open up neighborhoods and suburbs that are primarily single-family houses to more affordable town houses and apartments. This housing can benefit people already living in the area who wish to downsize or find a home for family members, or who work in the community but can’t afford to live there. A percentage of this housing can be subsidized, which can create choices for people who want to move out from the inner city but can’t afford a single-family house, or even a suburban apartment. Raising the density in these corridors to something like ten families to the acre can create a viable market for a transit line, probably bus rapid transit, which does not require the level of capital investment that would be needed for rail transit but can provide a comparable service.

Given the revolution currently going on in retail, it makes sense for communities to permit apartments and row houses in other commercial zones. Adding apartments to business centers can help create walkable mixed-use districts, which can be preferred places to live, as well as reinforcing office uses and providing more customers for shops and restaurants.

Row houses and apartments are currently being built out at the urban fringe, because it has been difficult to find suitable sites in established suburban communities. Opening more opportunities to build closer to traditional suburban and urban centers can take some of the development pressure off the edges of suburbia—making it easier to preserve the landscape and saving some of the cost of infrastructure and services that would otherwise be needed.

Metropolitan planning organizations would be a good forum for coordinating the rezoning of commercial corridors that run through multiple communities and funding the transit necessary to serve them.

Inclusionary Zoning: Zoning regulations have helped institutionalize segregated neighborhoods by using minimum lot sizes to differentiate residential zones. States and cities are beginning to address these housing inequalities.

What the press has called “eliminating single-family zoning” has recently become policy in Minneapolis and is the basis for a new law in Oregon; other states and cities are looking at similar measures.

Eliminating needs to be in quotes, as single-family houses continue to be legal, and new ones can still be built. In Oregon the change is to permit duplex housing units on what had been single-family lots in cities above ten thousand people, and up to four units will be permitted on some single-family lots in cities of more than twenty-five thousand people and in the Portland Metro area. In Minneapolis the adopted policy is to permit three housing units to be built on formerly single-family lots. These initiatives are intended to increase the supply of affordable housing and remove barriers that have kept lower-income people from living in large parts of cities and suburbs.

The big effect of allowing four units on a single-family lot is not going to be felt in neighborhoods of million-dollar homes. If it costs $1 million to acquire a property, and the developer intends to rebuild four houses or apartments, each will have to sell for $1 million to meet the typical real estate practice that the cost of land acquisition should not be more than a quarter of the purchase price. If fewer new units are permitted, the purchase price of new development will need to be even higher. However, if the acquisition cost of a house and lot is $200,000, four new units would need to be priced at only $200,000. These numbers tell us that the impact of permitting more units in single-family zones will occur mostly in modest areas where people might rent or own an older, small house on a lot that is big enough for redevelopment.

How the new development is managed will make a big difference for the future of these neighborhoods. A hands-off policy for denser development in established neighborhoods will be destructive as well as unpopular. The Toronto regulations mentioned on page 115 are a good example of a way to increase residential density in an established neighborhood by setting standards and reviewing proposals.

The option for an another, smaller dwelling unit on a single-family lot, either as part of the main house or a variation on what used to be called a garage apartment, is being added to the regulations in many cities. Again, standards and a review process can help maintain and enhance the good aspects of the existing neighborhood.

Mixing lot sizes within a zone, as mentioned earlier, makes it easier to lay out a subdivision without destructive stripping of vegetation and regrading taking place over an entire property. It also makes it possible to integrate more affordable housing within development as it takes place. The overall density requirement in residential units per acre remains the same and is enforceable when plans are reviewed for subdivision approval and continues to be enforceable when building permits are applied for. What changes is the minimum lot size, which could be reduced, for example, to one-sixteenth of an acre, the size of a typical row house lot. It would be much easier to preserve parts of the land that should not be built on, and the developer could easily end up spending less money on streets and other infrastructure. It would also be easier to design a walkable community, as some of the dwellings would be closer together, and it would also be easier to set aside a percentage of the units as subsidized housing. The normal approval process for a subdivision includes extensive review by the planning authorities. That review process should remain in place, and there ought to be standards for walkable mixed-lot-size communities to guide the review process.

Changes like those outlined in this chapter ought to be within the existing powers of most local governments. They are central to implementing an improved design for megaregions.

From Designing for the Megaregion: Meeting Urban Challenges at a New Scale by Jonathan Barnett. Copyright © 2020 Jonathan Barnett. Reproduced by permission of Island Press, Washington, D.C.

Jonathan Barnett is an emeritus professor of practice in City and Regional Planning, and former director of the Urban Design Program, at the University of Pennsylvania. He is an architect and planner as well as an educator, and is the author of numerous books and articles on the theory and practice of city design. Barnett is a fellow of the American Institute of Architects and a fellow of the American Institute of Certified Planners. He has been awarded the Dale Prize for Excellence in Urban Design and Regional Planning, the Athena Medal from the Congress for the New Urbanism, and the William H. Whyte Award from the Partners for Livable Communities for being a pioneer in urban design education and practice.



