Houston's great advantage, it turns out, is its ability to provide affordable living for middle-income Americans, something that is increasingly hard to achieve in the Big Apple. That Houston is a middle-class city is mirrored in the nature of its economy. Both greater Houston and Manhattan have about 2 million employees.
Basically: unless you are extremely wealthy, you can't live too big in NYC. Recent immigrants in NYC have a very low standard of living by American standards, but generally still well above what it was where they emigrated from. If you're a run of the mill native American with a 'normal' middle class job, your dollar stretches much farther in the home of The Geto Boys.