1 definition found rocklake - U.S. Gazetteer (1990) : Rocklake, ND (city, FIPS 67500) Location: 48.79066 N, 99.24498 W Population (1990): 221 (129 housing units) Area: 0.6 sq km (land), 0.0 sq km (water) Zip code(s): 58365