I don't know whether Bush deserves all the credit for this; after all, many of the improvements may result from the enforcement of national standards and the advent of better production technologies. But it is apparent that Texas, like most states, has improved the environment and that it ranks better than many states (and its cities better than many other cities) in what it has achieved.
You would think that before Gore unleashed his ads, he would have checked with Browner at the EPA to get the facts straight. Then again, maybe he did.
But there is only one real mystery here. Why did the national press ignore the incompatibility between Gore's claims and the real facts? If Bush had made similar charges about pollution in Tennessee, there is little doubt that the press would have put them under the microscope. Perhaps this is a way of explaining how valence issues really play out in presidential politics. If people agree that some goal is desirable, then how a candidate handles that issue will depend on what arguments the press will let slip by.
Recall what happened to Bush's father when a group supporting him ran the Willie Horton ads. It was an effort by those backing the elder Bush to suggest that on crime (another valence issue) he was closer to how people felt than was Michael Dukakis. The national press came down hard on Bush, claiming his argument was unfair or even racist. To the national media, crime is the "wrong" valence issue because being tough on crime (something that almost all Americans want) is the "wrong" reaction. But the environment is a good valence issue because being tough about it is the "right" reaction.
Whatever the merits of the two candidates, the Gore people understand the press better than do the Bush supporters. If Bush wins, this is a lesson he ought to take with him into the White House.