Sheridan is a city in northwest Worth County, Missouri, United States, near the Platte River. The population was 145 at the 2020 census. A post …Sheridan is a city in northwest Worth County, Missouri, United States, near the Platte River. The population was 145 at the 2020 census. A post office called Sheridan has been in operation since 1887. Sheridan was the name of a local family.