1948 is a year in the 20th century.
- November 21: Future United States Air Force Lieutenant Colonel Robert Budahas is born. (TXF: "Deep Throat")
- The Palomar Observatory in San Diego, California becomes the largest telescope in the world. It was designed by George Ellery Hale. According to legend, Hale gained the idea from an "elf" who visited his home while he was playing billiards. The elf told him to get the money from the Rockefeller Foundation. (TXF: "Little Green Men")
- Paula Gray is born in Dudley, Arkansas, the granddaughter of Walter Chaco. (TXF: "Our Town")
- In 1999, Fox Mulder was under the impression that Negro League baseball player Josh Exley had hit 60 home runs in 1948, when in fact it was 61 home runs in 1947. (TXF: "The Unnatural")