Lamont is a city in Buchanan County, Iowa, United States. The population was 429 at the time of the 2020 census. Lamont was first settled in 1…Lamont is a city in Buchanan County, Iowa, United States. The population was 429 at the time of the 2020 census. Lamont was first settled in 1841. A post office was established here in 1875. The Chicago Great Western Railway made it a stop on the railroad in 1886.