To study diversity, biologists often establish a transect. A transect is essentially a line across the landscape, along which diversity can be sampled and studied. We made a transect across Washington that extends from Cape Flattery, at the northwestern tip of the Olympic Peninsula, to the confluence of the Snake and Grand Ronde Rivers in southeastern Washington. In this program, we describe various locations along and near the transect to explore many of the plant communities and kinds of plants that are characteristic of Washington. At the end of the program, we provide a list of the locations so that you can explore firsthand the biological diversity of Washington.