Eaton is the county seat of Preble County, Ohio. William Bruce established the town in 1806. Residents named the community after General William Eaton, a hero of the American Revolution. The village grew quickly, having approximately one thousand residents in 1846. This growth was primarily due to Eaton's location along two main turnpikes, making it an important crossroads. Numerous Ohioans also traveled to Eaton to acquire sulfur water, which they believed had some medicinal curatives. In 1846, Eaton consisted of three churches, six stores, and at least one newspaper office. Many residents found employment in nearby limestone quarries. During this era, limestone was a common building material. Unfortunately for Eaton residents, in 1849, a cholera epidemic struck the community. Approximately one-half of the residents fled the community. Of the remaining six hundred people, approximately 120 people died.
Over the next several decades, Eaton's population doubled in size. In 1880, 2,143 people resided in the town, with one-third of these inhabitants being school-aged children, and in 1890, 2,996 residents inhabited the community. In 1886, two newspaper offices, seven churches, and two banks served the community. Most manufacturing establishments provided services or products to farmers in the surrounding countryside. Many Preble County farmers grew tobacco, and several businesses in Eaton manufactured cigars. F.P. Filbert, a cigar maker, was the town's largest employer, with thirty-five employees.
Throughout the twentieth century, Preble County residents found employment primarily in agriculture-related positions. Eaton residents continued to prosper by providing services and products to the farmers. Several residents also commute to Cincinnati to find employment. In 2000, Eaton was Preble County's largest urban center, with a population of 8,133 people.