What Houston lacks in zoning laws, it makes up for with many, if not most, neighborhoods being "deed restricted" communities. For residents, this is effectively the same as zoning. From the city website (http://www.houstontx.gov/legal/deed.html):

"Restrictions mean limitations that:

-Affect the use to which real property may be put;

-Fix the distance that a structure must be set back from property lines, street lines, or lot lines;

-Affect the size of a lot or the size, type and number of structures that may be built on the lot;

-Regulate orientation of a structure; or

-Regulate certain fences requiring a building permit."

Enforced zoning is just one of the cited laws encouraging sprawl. Houston still has many others:

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=837244

http://www.freepresshouston.com/parking-wars/

http://marketurbanism.com/2008/12/10/is-houston-really-unpla...

just because you eliminate the restrictions, doesn't mean the population will behave outside of the previous restrictions.

How dare you challenge an armchair city planner!