Fallon was named for Benjamin O'Fallon, a nephew of the explorer, William Clark. It was a Northern Pacific Railroad station along the Yellowstone River. Fallon is noted for its rich grain fields and in earlier days, the land was covered with buffalo grass that fed millions of bison. The first post office was established in the fall of 1884, closing in winter of that same year. It was then reopened in 1890 with Cyrus Mendenhall as postmaster.
Fallon is located in eastern Montana, between Miles City and Glendive on I-94.