Schuyler County is a county located in the northeastern portion of the U.S. state of Missouri. As of the 2020 census, its population was 4,032, making it the fourth-least populous county in Missouri. Its county seat is Lancaster. The county was organized February 14, 1845, from Adair County, and named for General Philip Schuyler, delegate to the Continental Cong…Schuyler County is a county located in the northeastern portion of the U.S. state of Missouri. As of the 2020 census, its population was 4,032, making it the fourth-least populous county in Missouri. Its county seat is Lancaster. The county was organized February 14, 1845, from Adair County, and named for General Philip Schuyler, delegate to the Continental Congress and U.S. Senator from New York.