[1] Eaton County is included in the Lansing-East Lansing, Metropolitan Statistical area in Central Michigan.

The county was named in honor of Gen. John H. Eaton, secretary of war in the cabinet of President Andrew Jackson.

The following summer (July 30, 1830), the Territorial Legislature changed Eaton's assignment, attaching it to Kalamazoo for administrative, revenue, and judicial purposes.

While the name "Belleville" was given to the first organized township, including the whole county, it does not appear to have been used in any official documents.

In 1832, a surveyor, George W. Barnes, bought a homestead in central Eaton County; that area is now contained in Charlotte.

On March 21, 1833, he applied to Territorial Governor George B. Porter for a commission to be appointed to locate the county seat: "That in the month of may last he put up in three public places in the county of Kalamazoo notices that application would be made to the governor of the territory of Michigan to appoint commissioners to locate a seat of justice for Eaton County, agreeably to the law in such cases made and provided."

However, population growth in Lansing and the surrounding area has made the county more competitive in recent years.

Barack Obama carried the county in both 2008 and 2012, as did Michigan governor Jennifer Granholm, a Democrat, in her winning gubernatorial campaigns of 2002 and 2006.

In 2014, Republican governor Rick Snyder narrowly lost the county while winning statewide.

The county government operates the jail, maintains rural roads, operates the major local courts, records deeds, mortgages, and vital records, administers public health regulations, and participates with the state in the provision of social services.

The county board of commissioners controls the budget and has limited authority to make laws or ordinances.

In Michigan, most local government functions — police and fire, building and zoning, tax assessment, street maintenance, etc.