One of the most important places in the United States where two plates are sliding past each other is in California along the San Andreas Fault. This fault line slices California in two. It begins in Cape Mendocino and runs south to the Mexican border. The fault is where the Pacific Palate and the North American Plate meet. The Eastern part of the plate which goes through San Diego, Los Angeles and Big Sur are on the Pacific plate and it is sliding North. The Western part of the plate which includes San Francisco, Sacramento and the Sierra Nevada mountain range are on the North American plate. It is sliding south. The movement is usually rather small, about one two two inches a year. However, once in a while, there is a large and/or fast movement which can result in an earthquake. The following link has a map of the fault line and more information.