OSCEOLA, a county in the N. W. part of Iowa, bordering on Minnesota Territory, has an area of about 535 square miles. It is drained by the head waters of the Little Sioux river which flows into the Missouri. This county is not included in the census of 1850. County seat not located. Named in honor of the celebrated Seminole chief Osceola. (Baldwin's New and Complete Gazetteer of the United States..., 1854)
OSCEOLA COUNTY Is situated in the northwestern portion of the State, being in the northern tier of counties and the second east from Nebraska. It is bounded on the east by Dickinson, on the south by O'Brien, and on the west by Lyon. It is watered by the headwaters of the Little Sioux and Rock Rivers. It is not yet organized. (Hair's Iowa State Gazetteer..., 1865)