In mountaineering in the United States, a thirteener (abbreviated 13er) is a mountain that exceeds 13,000 feet (3,962.4 m) above mean sea level, similar to the more familiar "fourteeners," which exceed 14,000 feet (4,267.2 m). In most instances, "thirteeners" refers only to those peaks between 13,000 and 13,999 feet in elevation.
The importance of thirteeners is greatest in Colorado, which has the majority of such peaks in North America with over 600 of them. Despite the large number of peaks, over 20 peak baggers have reported climbing all of Colorado's thirteeners.[1] Thirteeners are also significant in states whose highpoints fall between 13,000 and 13,999 feet. For example, the Wyoming thirteeners are the highest peaks within the state, and only 5 individuals have reported climbing all 35 peaks, likely due to a combination of technical difficulty and remoteness.[2][3] In 2019, Teresa Gergen became the first person to summit all 846 thirteeners outside of Alaska, an accomplishment that took her nearly two decades to complete.[4][5]
Not all summits over 13,000 feet qualify as thirteeners, but only those summits that mountaineers consider to be independent. Objective standards for independence include topographic prominence and isolation (distance from a higher summit), or a combination. However thirteener lists do not always consistently use such objective rules. A rule commonly used by mountaineers in the contiguous United States is that a peak must have at least 300 feet (91 m) of prominence to qualify. According to the Mountaineering Club of Alaska, it is standard in Alaska to use a 500 ft (152 m) prominence rule rather than a 300-foot rule. These are the standards applied for the lists below. Regarding whether or not peaks in excess of 13,999 feet should be considered as "thirteeners", this article will count them as such for statistical purposes, but concentrate its focus on those peaks less than 14,000 feet since the higher peaks are already covered in the fourteeners list.