But what if some of the people living on that block have been renting at low prices since before Neighborhood Main Street was such an exciting hub? If the building form remains as is with low levels of density, long-time renters may no longer be able to afford to live in that neighborhood because of rising rents responding to increasing housing demand. Residents of owner-occupied houses may also see this pressure, observe an increase in their property values, and oppose new development in their neighborhood so that competition for supply housing stock is restricted, making it easier for property owners to sell at higher prices and higher returns on their original investment.

Now suppose that the city government observes this situation and approves an upzoning of the district by two notches up to T5 Neighborhood Shallow Setback (T5N.SS), an even denser zone than T4N.MF. Now more diverse building types are allowed. Yet, sensing that real estate developers are lurking just around the corner, a seller’s market forms; property owners now set their selling prices at speculatively high levels. This makes it so that developers eventually charge higher rents to make up for the high front-end fixed costs, or prices are unreasonably high enough that little new housing supply actually gets built, contrary to the policy intentions.

Ultimately, traditional patterns of urban growth are more difficult to achieve when upzoning is a strenuous, piecemeal effort. In the majority of cases, the archetypal, walkable American boomtown in response to sudden economic opportunity is hardly a possibility.

An Alternative Route

What if our imaginary city adopted a Dynamic Zoning ordinance? This might read as:

If building footprints in a block reach 70% of maximum physical buildout* and if according to the American Community Survey 70% of households in that block’s Block Group are occupied by renters**, then within 60 days of the ACS data’s release, the Planning Department must increase the zoning of all parcels in that block by one transect zone. Within 90 days, the Planning Department must make a recommendation to the Planning Board and the City Council whether to modify the zoning of parcels within 500 feet of the Census Block Group, either by allowing more diverse uses or by increasing the zoning district to the next transect zone.

In our imaginary city, suppose ACS data was released on September 18. Then by mid-November, the city would have to adopt new zoning so that the block would look like this: