To amplify, for others reading this comment, it's not just about the area. There's a much more fundamental problem than the enormous expense that would be required to put transit over such a wide area. Namely, you don't have any of the sort of clustering around would-be transit stops that is needed to make them work.

That in turn means that you have fewer riders, because they have to drive (or walk several miles in ditches or dangerous sidewalks along the sides of boring, high speed roads with no shade in Houston climate) to the station. Even people who want to live close to the station are likely to find themselves unable, as the parking for all those drivers will be prioritized in the immediate vicinity of the station. And all those people, despite using transit, are still having to pay the enormous costs of owning and operating a car (an expensive proposition, even with all the built-in subsidies).

At the same time that the transit is dealing with fewer riders and a need for tons of parking, it will need to deliver fast trips, very frequent service, and very low prices. Why?

Well, in a place like NYC, you can assume transit, and decide: do I need to own a car? Isn't the totality of owning a car, having to store it, and having the stress of operating it in the city really a losing proposition? And then you hold onto those transit customers by (hopefully) not providing them sufficient disappointment to reconsider.

In Houston, where you would be driving to any transit stop, the question is completely different: having already gotten in my car and onto the highway (and paid for the car in the first place), should I get off the highway, pay for parking (hopefully), park, walk across the parking lot, pay for a ticket, wait for the next train to show up, sit next to someone in a train that's not able to climate control against extreme Houston conditions, wait through all the stops, hope the driver doesn't take a break at one of the stops (I wish I weren't serious about this), get to my stop, walk out, and (somehow)travel another mile to my destination without my car? Or should I just sit in traffic for 20 minutes and arrive at my destination, where there's ample free parking for Black Friday every day, with room to spare?

And that's not even the end of it. If in Houston, against all the odds, you decide to take transit, any walking you have to do in this thankless sequence of events is going to be done on heat islands (made for the cars), in boring environments (made for the cars), with no shade (keep trees away to keep the cars safe), and with no people (no one else crazy enough to join you.)

Maybe if we just allowed tolls and gas prices and parking fees to rise enough, rather than subsidizing them, the people of Houston would see the error of their ways and quit driving there. But they wouldn't stick around either; everyone with available resources would abandon the city en masse for a place that still supported their happy motoring way of life. Then you'd just leave the poor people behind, which would make urban poverty look like child's play by comparison.

What if we stopped the automobile subsidies nationwide by force of congress and a strong President? Once again, everyone with means would flee, but this time they would flee to a place that could survive without cars. So, in the first situation they go to Dallas, and in the second they go to New England.