The Sierra Nevada, as a natural region, does not have exactly defined borders. In particular, to the north, there is a wide transition zone where the Cascade Range and the Sierra Nevada meet. As a result, it is difficult to delineate a border between these two mountain ranges. This list uses the common definition of the Sierra Nevada as the mountain range extending from Fredonyer Pass in the north to Tehachapi Pass in the south. It is also difficult to delineate between the Sierra Nevada mountains, the range's foothills, and the Central Valley; this article also considers any elevated and hilly terrain east of the flat Central Valley to be part of the range. Areas outside those bounds may also be included if they are widely associated with the Sierra Nevada.