Yermo is an unincorporated town and census-designated place in the Mojave Desert in San Bernardino County, California. It is 13 miles east of Barstow on Interstate 15, just south of the Calico Mountains. Its population was estimated at 1,750 in 2009. Founded in 1902 and originally named Otis, Yermo is situated at a division point of the Los Angeles and Salt Lake Railroad, later the Union Pacific Railroad line. A post office was established three years later with William J. Flavin serving as Yermo's first postmaster.