St. Marks is an unincorporated community in Sedgwick County, Kansas, United States. As of the 2020 census, the population of the community and nearby areas was 124. It is located about 4 miles (6 km) southwest of Colwich along 29th St N between 183rd St W and 199th St W, also it is located 5 miles (8 km) north of Goddard.