1 definition found three forks - U.S. Gazetteer (1990) : Three Forks, MT (town, FIPS 73975) Location: 45.88937 N, 111.55368 W Population (1990): 1203 (549 housing units) Area: 3.1 sq km (land), 0.1 sq km (water) Zip code(s): 59752