Even as Hurricane Harvey's floodwaters were still rising, dozens of pundits strongly in favor of land-use regulation started blaming Houston's flooding on the Bayou City's famous lack of zoning. ProPublica, for example, argued that Houston's "utter lack of zoning" contributed to the severity of the flooding. If land-use planning made Houston more compact, the pro-zoning argument goes, it would be better protected from floodwaters by surrounding prairielands.

No land-use planning regime can protect a region of 6.5 million people from the largest deluge of rain in U.S. history. The idea that traditional planning could have reduced the toll caused by more than four feet of rain both overstates Houston's freedom from land-use regulation and mistakes the actual consequences of its unique approach to land-use regulation.

In practice, Houston's development policy isn't as different as advertised from that of other major American cities. In the ways it does differ, it may allow for denser urban development rather than causing more sprawl into flood-prone areas.

While most cities control land use though their zoning codes, Houston's existing regulations serve a similar function. Its sprawling freeways and roads are accompanied by onerous parking requirements, just like the zoned cities of Los Angeles, Seattle, Chicago and Dallas. Each bedroom in a Houston apartment building must come with 1.25 parking spots. Restaurants must have eight spots per 1,000 square feet and bars must provide 10 spots per 1,000 square feet.

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Houston policy also requires that buildings have large setbacks from street lines. These policies work together to lead developers to build surface lots in front of their buildings rather than landscaping or making more efficient use of their land with parking garages. Combined with its parking requirements, Houston's setback mandates make it much more difficult to provide denser urban development.

Additionally, Houston has minimum lot size requirements that function much the same as the single-family zoning that most U.S. cities use to block development of multifamily housing in existing neighborhoods. In parts of Houston, homes must sit on lots that are at least 5,000 square feet. This rule, combined with Houston's highway network and government-mandated parking lots, outlaws compact development outside of the city center.

There are some ways in which Houston is legitimately lenient in its zoning regulation, yet these can encourage, not discourage, the type of dense development its critics are calling for.

Houston's absence of a zoning map has allowed the city to accommodate more housing and people within its city limits over time. In 1999, city policymakers implemented a reduction in minimum lot size requirements from 5,000 to 1,400 square feet for the part of the city that lies within Interstate 610. This has made it legal for developers to replace single-family homes with townhomes, allowing more people to live downtown rather than in new suburban development.

Houston's relatively laissez faire land-use policy has made it possible for the city to accommodate 500,000 additional residents within its borders in the past 30 years. This compares to just 100,000 new residents in San Francisco, another city with very high housing demand but without Houston's relative permissiveness toward development.