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. 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. 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.
