Frankford is a city in Pike County, Missouri, United States. The population was 323 at the 2010 census. A post office called Frankford has been …Frankford is a city in Pike County, Missouri, United States. The population was 323 at the 2010 census. A post office called Frankford has been in operation since 1830. The community's name probably is a transfer from Frankfort, Kentucky, the former home of a first settler.