There is an often-quoted tale that the name arose from an incident in which an Apache chief's daughter, Kari, was beloved by a brave called Tocom is pure fiction. The name's real origin is obscure, but the consensus is that it comes from a Plains Indian word meaning "lookout" and was applied to Tucumcari Mountain, 4,956 ft., the dramatic natural lookout just 2 miles south of town.
Efforts to trace the name to specific words in a specific Indian language, however, have been inconclusive. As T.M. Pearce summarized after his investigation: "The most convincing explanation is contributed by Elliott Canonge, Oklahoma linguist, who writes that the name is Comanche tukamukaru, 'to lie in wait for someone or something to approach.' According to Felix Kowena, his Comanche informant, this particular mountain was frequently used as a lookout by Comanche war parties."
Fray Angelico Chavez discovered a 1777 burial record mentioning a Comanche woman and her child captured in a battle at Cuchuncari, apparently an early version of Tucumcari. But other etymologies also are possible; a West Texas anthropologist believes it comes from a Kiowa word meaning "breast."
The town of Tucumcari appeared much later than the name. In 1901 the Chicago, Rock Island & Pacific railroad extended its line to here, and half the population of nearby Liberty moved to the unnamed tent city. Prairie winds caught clothing and rags and scattered them among the brush, giving the town its first nickname, Ragtown. The camp's saloons and gambling halls soon attracted outlaws and rowdies, and before long the camp had another nickname, Six-shooter Siding.
The town's first formal name was Douglas, given for reasons unknown, but this was short-lived, and soon the name Tucumcari was adopted. Tucumcari Lake, immediately north and east of Tucumcari, is a large natural lake, for centuries a watering place for Indians, comancheros, and cattle drivers on the Goodnight-Loving Trail.
From “The Place Names of New Mexico” Revised Edition, by Robert Julyan
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