McKittrick is a city in Montgomery County, Missouri, United States. The population was 77 at the 2020 census. McKittrick was laid out in 189…McKittrick is a city in Montgomery County, Missouri, United States. The population was 77 at the 2020 census. McKittrick was laid out in 1895 when the railroad was extended to that point. A post office called McKittrick was established in 1894, and remained in operation until 1967.