El Yunque - the only rain forest in the US Forestry system of parks
Correction: not the only rain forest in the system. There are some in both Hawaii and Washington.
Not to mention Alaska, home of the largest National Forest: http://www.fs.fed.us/r10/tongass/
What do you think the Olympic National Park is in Washington State? Chopped Liver? Much of the park is designated as rain forest, albeit not TROPICAL rain forest. However, as stated before Hawaii has tropical rain forest.