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A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. Mathematically, a summit is a local maximum in elevation. The topographic terms "acme", "apex", "peak", and "zenith" are synonymous.
The term "summit" is generally used only for a mountain peak with some significant amount of topographic prominence (height above the lowest point en route to the nearest higher peak) or topographic isolation (distance from the nearest point of higher elevation); for example, a boulder next to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are often considered subsummits (or subpeaks) of the higher peak, and are considered as part of the same mountain. The UIAA definition is that a summit is independent if it has a prominence of 30 metres (98 ft) or more; it is a mountain if it has a prominence of at least 300 metres (980 ft). This can be summarised as follows:
|Subpeak||< 30 m||? m|
|Independent peak or summit||30 m or more||? m|
|Mountain||300 m or more||? m|
In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit (not to be confused with Donner Pass, which is just to the south) while the highest point on Interstate 5 is Siskiyou Mountain Summit.