The Cincinnati metropolitan area (also known as the Cincinnati Tri-State area or Greater Cincinnati) is a metropolitan area with its core in Ohio and Kentucky.^[4][5] Its largest city is Cincinnati and includes surrounding counties in the U.S. states of Ohio, Kentucky, and Indiana.

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Greater Cincinnati Cincinnati, OH–KY–IN Metropolitan Statistical Area
Metropolitan Statistical Area
Downtown Cincinnati along the Ohio River, viewed from Devou Park in Covington, Kentucky.
Map of Cincinnati–Wilmington, OH–KY–IN CSA   City of Cincinnati   Cincinnati, OH–KY–IN MSA   Wilmington, OH µSA
Country	United States
State	Ohio Kentucky Indiana
Largest city	Cincinnati
Counties	List In MSA: Hamilton County Butler County Warren County Clinton County Clermont County Brown County Kenton County Campbell County Boone County
Area
• Total	4,808 sq mi (12,450 km2)
Elevation	551 ft (168 m)
Population  (2015)[1]
• Metro density	469/sq mi (181/km2)
• MSA	2,256,884 (28th)[2]
	MSA/CSA = 2015, Urban = 2013
GDP [3]
• MSA	$186.1 billion (2022)
Time zone	UTC−5 (EST)
• Summer (DST)	UTC−4 (EDT)
Area code(s)	513, 283, 859, 937, 812

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The United States Census Bureau's formal name for the area is the Cincinnati, OH–KY–IN Metropolitan Statistical Area. As of the 2020 U.S. Census, the metro area had a population of 2,256,884, making Greater Cincinnati the 28th-most populous metropolitan area in the United States, and the largest metro area in Ohio, followed by Columbus and Cleveland.^[6] The Cincinnati–Wilmington, OH–KY–IN Combined Statistical Area, adds Clinton County, Ohio (defined as the Wilmington, OH micropolitan area) and, until 2023, Mason County, Kentucky (defined as the Maysville, KY micropolitan area), was part of the CSA.^[7] The Cincinnati metropolitan area is considered part of the Great Lakes Megalopolis.

The Cincinnati metropolitan area was originally designated by the United States Census Bureau in 1950 and consisted of the Kentucky counties of Campbell and Kenton and the Ohio county of Hamilton. As surrounding counties saw an increase in their population densities and the number of their residents employed within Hamilton County, they met Census criteria to be added to the MSA. The Hamilton–Middletown, OH MSA was also formed in 1950 and consisted solely of Butler County, Ohio.

In 1990, the Census changed designation of the areas known as MSAs to Primary Metropolitan Statistical Area (PMSA), and a new Consolidated Metropolitan Statistical Area (CMSA) grouping was created. From 1990 through 2005, the Cincinnati–Hamilton–Middletown CMSA included the Cincinnati–Hamilton, OH–KY–IN PMSA and the Hamilton–Middletown, OH PMSA.

As of December 2005, Census terminology changed again, eliminating the PMSA/CMSA terminology. Consolidated Statistical Areas (CSA) combine more than one Core Based Statistical Area (CBSA). Newly defined MSAs (Metropolitan) and µSAs (Micropolitan) Statistical Areas are CBSAs. From 2005 to 2013, the Cincinnati–Middletown–Wilmington CSA included the Cincinnati–Middletown MSA (defined as the old Cincinnati–Hamilton–Middletown CMSA), and Wilmington, OH µSA (Clinton County, Ohio).

In 2013, the CSA was redefined again. The Cincinnati–Middletown MSA was renamed the Cincinnati MSA. The Wilmington, OH µSA remained in the CSA. The Maysville, KY µSA, which had previously consisted of Mason and Lewis Counties in Kentucky, was redefined as consisting solely of Mason County and added to the CSA. The name of the CSA accordingly changed to the Cincinnati–Wilmington–Maysville CSA.

In September 2018, Union County, Indiana, was added to the Cincinnati MSA.^[8]

In July 2023, the new metropolitan area delineation were published and Union County, Indiana, was detached from the Cincinnati MSA, and the Maysville, Kentucky, micropolitan statistical area was detached from the combined statistical area.^[9]

Most of the region's population growth has occurred in the northern counties, leading to speculation that the Cincinnati–Northern Kentucky metropolitan area will eventually merge with Greater Dayton.^[10] Cincinnati is also located very close to other metropolitan areas, such as Columbus, Indianapolis, Lexington, and Louisville.

Notes
¹For comparison purposes, population data is summarized using 2008 Census CSA/MSA county definitions.
²Butler County, Ohio was previously known as the Hamilton–Middletown, OH PMSA and was separate from the Cincinnati, OH–KY–IN PMSA until the 1990 Census, when the Cincinnati–Hamilton, OH–KY–IN CMSA designation was used to consolidate the two PMSAs. The CMSA/PMSA designation is no longer used by the US Census.

Population figures as of the 2020 census.

The Cincinnati–Northern Kentucky metropolitan area is located within a climatic transition zone. The southern area of the region, from roughly about the Ohio River, is at the extreme northern limit of the humid subtropical climate; the north part of the region is on the extreme southern cusp of the humid continental climate. Evidence of both humid subtropical climate and humid continental climate can be found here, particularly noticeable by the presence of plants indicative of each climatic region. Within the area, the USDA climate zone rating can vary from as warm as zone 6b^[13] to as cool as zone 5b,^[14] with the warmest areas tending to be found closest to the Ohio River; individual microclimates of even cooler and warmer temperature may occur in the area but are too small to be considered in the overall climate zone rating. The common wall lizard, introduced from Italy in the 1950s, is an example of fauna in the area that lends a subtropical ambiance to the urban core (near downtown Cincinnati) area of the region.

Significant moderating variables for the overall climate are:

• South and central: Ohio River, Licking River, relatively large hills and valleys, and a combined urban heat island effect due to the close proximity of the Cincinnati-Northern Kentucky cities of Covington, Newport, and Downtown Cincinnati
• Suburban: large parking lots that take up much land in Mason, West Chester, and Florence create a heat island effect.
• North: Great Miami River, the area is situated on a glaciated flat plateau, the Miami Valley, and some urban heat island effect in the immediate area of downtown Dayton and Hamilton.

Traveling through the region from North to South, a subtle but interesting change in climate can be observed and is most evidenced by the gradual increase in the occurrence of subtropical indicator plants in the landscape. Most noticeable are the Southern Magnolia and Mimosa trees, and the needle palm also may be found as a winter hardy landscape specimen in lawns near the Ohio River. During the winter, travellers from north to south will routinely observe a significant difference in snowfall/ice/rain in the region.

Although widely accepted as part of the Midwestern United States, the Cincinnati–Northern Kentucky metropolitan area is climatically and geographically located on the northern periphery of the Upland South region of the United States and is within the Bluegrass region of Ohio and Kentucky.

The area is vulnerable to occasional severe weather—thunderstorms, large hail and sometimes tornadoes.

• 513 and 283 – Ohio counties and Cincinnati
• 937 and 326 – Ohio counties
• 859 – most Kentucky counties
• 606 – Bracken and Mason counties, Kentucky
• 812 and 930 – Indiana counties
• 765 – Indiana counties

Cincinnati-based broadcast media outlets often use the terms "Greater Cincinnati" and "Tri-State Area" to refer to their broader viewing or listening areas, especially for the purpose of weather reports or school closings. The viewing areas of WLWT, WCPO-TV, and WKRC-TV all span the same 26 counties, including Adams and Highland counties in Ohio; Fayette, Ripley, Switzerland, and Union counties in Indiana; and Carroll, Owen, and Robertson counties in Kentucky.^[26][27][28] WXIX-TV additionally includes Decatur County in Indiana and Lewis County in Kentucky.^[29]

Dayton-area media outlets similarly refer to a Miami Valley area that includes Butler and Warren counties in Ohio and sometimes Clinton County, Ohio, and Union County, Indiana.