Republic is an unincorporated community in Marquette County in the U.S. state of Michigan. It is also a census-designated place (CDP) for statistical purposes, covering a narrow, roughly crescent-shaped area along several miles of M-95. Most of the CDP is within Republic Township, although a small portion of the CDP extends north into Humboldt Township Republic is also the name of the post office for ZIP code 49879, which includes the CDP as well as most of the rest of Republic Township and a small portion of Mansfield Township in Iron County. The population of the CDP was 614 at the 2000 census. The population of the 49879 ZCTA in 2000 was 996.