Frankfort is a city in Marshall County, Kansas, United States. As of the 2010 census, the city population was 726.
Frankfort is located at 39°42′14″N 96°25′5″W / 39.70389°N 96.41806°W / 39.70389; -96.41806 (39.703810, -96.417925). According to the United States Census Bureau, the city has a total area of 1.0 square miles (2.6 km²), all of it land.
As of the census of 2000, there were 855 people, 367 households, and 230 families residing in the city. The population density was 842.2 people per square mile (323.6/km²). There were 411 housing units at an average density of 404.8 per square mile (155.6/km²). The racial makeup of the city was 98.25% White, 0.35% African American, 0.12% Native American, 0.12% Pacific Islander, and 1.17% from two or more races. Hispanic or Latino of any race were 0.35% of the population.