city, seat (1899) of Otero county, southern New Mexico, U.S. It lies at the western base of the Sacramento Mountains and east of the Tularosa Basin. Founded by John A. and Charles B. Eddy in 1898 and named for its large cottonwood trees (Spanish: alamo "cottonwood," gordo "fat"), it became a division point on the Southern Pacific Railroad and developed as a lumber town and agricultural-market centre. The Holloman Air Force Base was constructed there during World War II, and the first atomic bomb was exploded at the "Trinity Site" (60 miles [97 km] northwest) on July 16, 1945 (see ). The base later tested guided missiles, and it now houses aerospace research facilities.
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