Marion County, Indiana

Marion County is a county in Indiana, United States, consolidated since 1970 with the city of Indianapolis under the Unigov city-county government. It had a population of 977,203 at the 2020 census, an estimated 992,196 by 2025, and covers 396.30 square miles (1,026.4 km2) of land centred near 39°47′N 86°08′W.

Indianapolis is the county seat and the state capital; its downtown postal code is 46204. Unigov merged most city and county functions in 1970, but four cities and one town still elect their own governments as excluded municipalities, and eleven small towns keep limited local powers as included towns. The county holds 16 such municipalities in all, and it runs on Eastern Time. Its FIPS code is 18097.

Towns & Villages in Marion County

Marion County has 16 legally distinct municipalities: the consolidated city of Indianapolis, four excluded cities and towns that kept their own elected governments when Unigov formed, and eleven included towns that kept some local powers — taxation, policing, street maintenance — while joining the countywide city-county council. There are no census designated places in Marion County; everything inside the county line is part of one municipality or another.

Cumberland (marked with an asterisk) straddles the Marion–Hancock county line; its 5,954 residents are countywide, and most of the town’s land now sits in Hancock County, though its center and its status as an included town remain tied to Marion. Crows Nest and North Crows Nest are two adjoining included towns near Butler University; the Census Bureau does not publish a separate population count for either, since both are small enough to fold into surrounding tract data. Older lists of Marion County places also mixed in dozens of unincorporated Indianapolis neighborhoods and subdivisions — Broad Ripple, Irvington, Nora, Castleton, Oaklandon, Traders Point, West Newton, Augusta, Bridgeport, Ben Davis and Millersville among them. These are real, long-standing communities, but none has its own government, boundary or census population separate from Indianapolis; they are neighborhoods within the consolidated city, not municipalities, so they are not listed as separate rows above.

ZIP Codes

Indianapolis alone uses 57 ZIP codes, running from 46201 through 46298, with 46204 covering the Mile Square downtown core around the City-County Building. The four excluded cities and Speedway keep ZIPs of their own: 46226 (plus 46216, 46235 and 46236) for Lawrence, 46107 for Beech Grove, 46224 for Speedway, and Southport shares Indianapolis-administered ZIPs on the county’s south side. Among the included towns, Clermont uses 46234, Warren Park 46219, Williams Creek 46240, Wynnedale 46228 and Cumberland 46229; Meridian Hills, Homecroft, Rocky Ripple, Spring Hill, Crows Nest and North Crows Nest are all small enough that mail there is delivered under a neighboring Indianapolis ZIP rather than a code of their own.

Geography

Marion County sits at the center of Indiana on the Tipton Till Plain, a flat to gently rolling glacial plain that covers most of the central part of the state. Of the county’s 403.01 square miles, 396.30 are land and 6.71 are water, about 1.7 percent, mostly the White River and its tributaries. The White River runs southwest through the county and through downtown Indianapolis, joined by Fall Creek, Eagle Creek, Pleasant Run and Pogues Run; the Central Canal, dug in the 1830s for a canal system that was never finished, still supplies part of the city’s water and threads through several north-side neighborhoods.

Hamilton County lies to the north, Hancock County to the east, Shelby County to the southeast, Johnson County to the south, Morgan County to the southwest, Hendricks County to the west and Boone County to the northwest. Hamilton County, Hancock County, Shelby County, Johnson County, Morgan County, Hendricks County and Boone County all border Marion directly.

Demographics

Marion County had a population of 977,203 at the 2020 census, the largest of any county in Indiana, and the latest estimate puts it near 992,196 residents. Indianapolis itself accounts for 887,642 of that total, with Lawrence a distant second at 49,370. Median household income runs $66,346, below Indiana’s statewide figure of $69,477. Population density works out to roughly 2,465 people per square mile of land, by far the highest in the state and typical of a fully urbanized, consolidated city-county.

Economy & Local Life

Health care and social assistance employs the most workers in the county, about 72,429 people, followed by retail trade at 58,090 and manufacturing at 53,748. Eli Lilly and Company, a pharmaceutical maker founded in Indianapolis in 1876, remains headquartered downtown and is the county’s best-known private employer. Elevance Health (formerly Anthem) and Indiana University Health both run major operations centered in the city, and Indianapolis International Airport hosts one of FedEx’s largest air-cargo hubs, driving substantial logistics and warehousing employment on the county’s southwest side. Beech Grove is still built around the Amtrak-operated Beech Grove Shops, a railroad repair complex dating to 1906, and Speedway’s economy centers on the Indianapolis Motor Speedway. The county’s biggest annual event is the Indianapolis 500, run at the Speedway each May and billed as the world’s largest single-day sporting event.

History

The Indiana General Assembly organized Marion County on 1 April 1822, naming it for Francis Marion, a South Carolina brigadier general in the American Revolutionary War known as the “Swamp Fox.” Indianapolis was platted the same year as the new state capital, chosen for its central location rather than any existing settlement, and became the county seat.

The county’s modern shape dates to 1 January 1970, when the Indiana legislature created Unigov, merging most City of Indianapolis and Marion County government functions into a single city-county administration with an elected mayor and a 25-member city-county council. Four existing cities and towns — Beech Grove, Lawrence, Southport and Speedway — were allowed to keep their own governments as excluded municipalities, and eleven smaller incorporated towns kept limited local powers as included towns. Unigov remains one of the most extensive city-county consolidations in the United States.

Getting There

Five interstates cross the county: I-65, I-69, I-70 and I-74 converge on downtown Indianapolis, and I-465 rings the city as a beltway connecting all of them.

• Downtown Indianapolis — central, all distances below measured from here
• Carmel — about 15 miles north
• Greenwood — about 12 miles south
• Plainfield — about 15 miles west

Indianapolis International Airport, about 8 miles southwest of downtown, is the county’s major commercial airport and one of the country’s busiest cargo hubs. Amtrak’s Cardinal service stops three times a week at Indianapolis Union Station downtown, connecting to Chicago and Washington, D.C.

Frequently Asked Questions

Where is Marion County located?
It sits at the center of Indiana, bordered by Hamilton, Hancock, Shelby, Johnson, Morgan, Hendricks and Boone counties, with Indianapolis as its seat.

What is the population of Marion County?
977,203 at the 2020 census, with a 2025 estimate near 992,196 — the largest population of any Indiana county.

How big is Marion County?
403.01 square miles in total, of which 396.30 square miles are land.

What is the county seat of Marion County?
Indianapolis, also Indiana’s state capital, is the county seat.

How many towns and cities are in Marion County?
Sixteen: the consolidated city of Indianapolis, four excluded cities and towns (Beech Grove, Lawrence, Southport and Speedway), and eleven included towns such as Clermont, Cumberland and Meridian Hills.

What ZIP codes does Marion County use?
46201 through 46298 for Indianapolis, plus 46107 for Beech Grove, 46224 for Speedway, 46226 for Lawrence and separate codes for several included towns.

What is Unigov?
Unigov is the 1970 consolidation of most City of Indianapolis and Marion County government functions into one city-county administration, the arrangement that still shapes the county today.

More counties in this state: Towns and villages in Indiana.