Species	Area Where Found	Problems for the Species
High-elevation spruce and fir	Appalachian Mountains, Eastern US	Low growth rates, mortality
Southern pines	Southeast US	Low growth rates
Sugar maples	Northeast US, Southeast Canada	Death of top branches, lower syrup production
Ponderosa, Jeffrey Pines	California	Death, low growth rate, and regeneration

Source: The New York Times, May 15, 1991, p. A10

The table above lists some species in the United States whose existence is being threatened by high levels of air pollution.  The table lists the species, where in the US it is found, and the specific reason that it is endangered.

All of the species in the list are trees.  The reasons that they are threatened are similar in most cases.

However, the species are spread throughout the United States.  This shows that air pollution is a major pollution in all parts of the country, not just a few.