Edgar is a census-designated place and unincorporated community in Carbon County, Montana, United States. As of the 2010 census it had a population of 114. Although it is unincorporated, Edgar has a post office with a ZIP code of 59026.. The post office was established May 28, 1909 with John J. Thornton as its first postmaster.
Edgar lies east of the intersection of U.S. Route 310 and Elwell Street. Edgar is south of Rockvale and northeast of Fromberg. Edgar is a small, agricultural community with a number of silos and elevators. It is also home to a bar & grill restaurant and some other services.