Read on Twitter
Excited to share that my paper on Houston's 1998 subdivision reform with @AA_Millsap is out today in the Journal of Planning Education and Research! Here are some of our high-level findings. (Thread) https://journals.sagepub.com/doi/full/10.1177/0739456X20935156
Houston is unique in not having zoning, which means it doesn't segregate uses or restrict density. But it does have subdivision regulations, which deal with minimum lot size, a major driver of housing costs. Until 1998, Houston enforced an MLS of 5,000 SF. https://www.strongtowns.org/journal/2019/6/19/do-minimum-lot-size-rules-matter
Before 1998, between MLS rules, setbacks, and parking requirements, every detached single-family home had to take on a conventional post-war form. And townhouses were practically difficult.
But in 1998, the city dropped the MLS down to 3,500 as-of-right, or as low as 1,400 SF with liberal open space set asides. This made the development pattern that is reshaping Houston today possible and has produced ~25,000 units. One house could turn into three townhouses.
Why did this happen? On the one hand, the market needed more housing as populations and incomes boomed. On the other hand, planning leadership wanted to support densification/walkability trends. Even before reform, lot size variances were going out like candy.
But why didn't homeowners scuttle such a dramatic reform (a 72% reduction in MLS!) as they do in most cities? Part of it has to do with why Houston doesn't have deed restrictions in the first place: folks with extreme land-use preferences are already "protected," so to speak.
As part of the broader reform, the city allowed local blocks to adopt a local "special minimum lot size" tracking on to the prevailing lot size, as a way of "opting out" of reform. As with deed restrictions, this effectively mediated opposition to the citywide liberalization.
But there's a risk here: with some of the richest neighborhoods "opting out" of reform, wouldn't developers shift their focus to marginalized areas with cheap land?
That doesn't seem to have happened: post-reform development activity (i.e. sub-5,000 SF lots) was heavily concentrated in middle-income residential areas and underbuilt former-industrial and -commercial neighborhoods near job centers.
Before reform, non-compliant sub-5,000 SF lots were concentrated at statistically significant rates in neighborhoods like Greater East End. These lots were "legalized" by the reforms.
After reform, subdivision activity was heavily concentrated in Houston's middle-class, predominantly white northwest, as well as underbuilt lots in Downtown and Midtown. (To be clear, we did not find a significant relationship with race one way or another.)
Indeed, there was surprisingly no relationship between where pre-1998 sub-5,000 SF lots existed and where post-1998 sub-5,000 SF lots were platted over the past ~20 years.
What are the key takeaways for practice? First, minimum lot sizes do matter...a lot. As @salimfurth and I have shown elsewhere, they serve to force up lot sizes, raising housing costs and pricing some segment of possible buyers out of the market. https://www.mercatus.org/publications/urban-economics/do-minimum-lot-size-regulations-limit-housing-supply-texas
Second, for all its issues, providing those homeowners with the most extreme anti-liberalization preferences with a highly local "opt out" provision might help to clear a path for broader, more meaningful reforms than might otherwise be possible.
Finally, post-reform development patterns suggest that citywide reforms are more likely to concentrate redevelopment in middle-income residential neighborhoods and underbuilt areas. If this ameliorates gentrification concerns, it may rekindle traditional disinvestment concerns.
Obviously striking the right balance on a lot of these issues will depend heavily on local conditions. It's up to planners and local policymakers to think through what "opt out" compromises they will sign on to, balancing development etc. No reform is perfect.
But the Houston 1998 subdivision reform *is* exceptional to the extent that (to my knowledge) it's the only reform in recent history that has dramatically increased densities in middle-income, low-density neighborhoods. And if only for that reason, it's worth studying. (/Thread)
