Your Guide to Union County, Ohio
Looking for trusted businesses, services and local resources in Union County, Ohio? FindItOhio.com helps residents and visitors discover local companies, professionals and community information across Union County, including Marysville, the county seat.
Quick answer: Union County is one of Ohio’s 88 counties. Its county seat is Marysville, it was established in 1820, and it has an estimated 73,446 residents as of 2025.
At a Glance
- County seat: Marysville
- Established: Apr 1, 1820
- Formed from: Delaware, Franklin, Logan, and Madison Counties
- Named for: Its formation by a union of four counties
- Estimated population (2025): 73,446
- Total area: 436.65 sq mi
- FIPS code: 39159
About Union County
Union County is a county located in the U.S. state of Ohio. As of the 2020 census, the population was 62,784. Its county seat is Marysville. Its name is reflective of its origins, being the union of portions of Franklin, Delaware, Madison, and Logan counties. Union County is part of the Columbus, Ohio Metropolitan Statistical Area.
History of Union County
Union County has been under the rule of three countries in its history: France, England, and the present day United States. It was discovered by the French explorer La Salle, along with traders and missionaries who accompanied him. After the French and Indian War, the Treaty of Paris of 1763 placed the area under British rule. Following the American Revolution, in 1783, the area would eventually become known as the Northwest Territory and part of the United States.
After the American Revolution, former soldiers from New England poured into Ohio after being granted land by the government. They surveyed the land, and sought to develop a state between Lake Erie and the Ohio River. Their proposals for the governance of the territory led to the passage of the Ordinance of 1787, which guided the establishment of states within the Northwestern Territory. Bitter struggles with American Indians over the next decades would follow, culminating with the battle of Tippecanoe in 1811, which saw the final defeat of the American Indian tribes in Ohio led by Tecumseh. A notable victim of the warring between the settlers and Indians was Jonathan Alder, who resided in and around the Union County area throughout his life.
Cities and Villages in Union County
Cities
Dublin, Marysville â€
Villages
Magnetic Springs, Milford Center, Plain City, Richwood, Unionville Center
Find Local Businesses in Union County
Browse the FindItOhio.com business directory to find restaurants, contractors, professional services, shops and more serving Union County. Own a business here? Add your free business listing so local customers can find you.
Background Checks, Process Serving and Private Investigations
Residents and employers in Union County can get BCI and FBI LiveScan fingerprinting, FD-258 fingerprint cards, process serving and licensed private investigations from these Ohio providers:
- Ohio Security & Investigations, Youngstown: licensed private investigations and fingerprinting. Call (888) 341-6960 or visit ohioinvestigators.com.
- 10-8 Protective Services, Columbus: investigations, fingerprinting and process serving. Call (800) 949-8521 or visit 10-8protectiveservices.com.
Frequently Asked Questions
What is the county seat of Union County, Ohio?
Marysville is the county seat of Union County, Ohio.
When was Union County established?
Union County was established on Apr 1, 1820. It was formed from Delaware, Franklin, Logan, and Madison Counties.
Who or what is Union County named for?
Union County is named for Its formation by a union of four counties.
How many people live in Union County, Ohio?
Union County has an estimated population of 73,446 as of 2025.
What cities are in Union County, Ohio?
Cities in Union County include Dublin, Marysville †.
Where can I find local businesses in Union County?
Search the FindItOhio.com business directory to find local businesses and services in Union County, Ohio.
How do I list my Union County business on FindItOhio.com?
Visit the free business listing page on FindItOhio.com and submit your business name, address, phone number and website.
Looking for another county? Explore all 88 Ohio counties on FindItOhio.com.
County background adapted from the Wikipedia article Union County, Ohio, available under the Creative Commons Attribution ShareAlike 4.0 license.