Poverty can be an indicator of people stranded in an environment where they cannot afford to move away to one with jobs, or it can be an indication of people attracted to an environment where they can improve their lives at a lower cost of living.
In a large enough geography there can of course be both dynamics at play.
If a place's population increased and the impoverished population shot up, then, at first, it would give me pause that perhaps people were getting stuck there. It wouldn't be the first time that brain drain happened in advance of urban retooling and job loss. Witness the great brain drain from the rural US into inner city manufacturing neighborhoods while factory jobs were already beginning to leave those city centers. The successful cities of England's North endured something similar at the same postwar moment in their much longer history.
That Texas keeps showing this behavior of parallel growth in popularity and poverty for decades on end, though, makes much more explanatory the latter idea -- that e.g. metropolitan San Antonio is popular and a ladder for the underdogs of both the American economy and several Central American ones. California had a very similar and bipartisan growth dynamic in the 1910s-1980s before some Californians started pulling up the ladder behind them. Would be interesting to see a trajectory of housing costs near job growth in that state over time and whether land offers Texas any real buffer against such a trajectory.
