- Los Angeles County in California has more people than any other county in the US
- The most recent US Census estimates, which were used in this story, are from July 2018.
- Kings County, New York, home of the Brooklyn borough, is the largest county in New York state.
- Visit INSIDER.com for more stories.
You may know the largest city in every state but when it comes to counties, there can be a lot of surprises. We’ve rounded up the largest county, based on population numbers, in every state, so you don’t have to do all of the hard work.
It’s important to note that these are subject to change as different areas boom and grow but is based on the most-recent Census estimates available from 2018.
Jefferson County, Alabama
The US Census reports that there are 659,300 residents living in Jefferson County, Alabama. This makes it the largest county in the southern state. Jefferson County is also home to Birmingham, the capital of Alabama.
Anchorage Municipality, Alaska
Maricopa County, Arizona
Over 4.4 million people call Maricopa County, Arizona home. Maricopa County includes Phoenix, the state’s capital, and is located in the southern central region of the Grand Canyon. State.
Pulaski County, Arkansas
Home to Little Rock – the capital of Arkansas and site of the William J. Clinton Presidential Library and Museum – Pulaski County is the most populous county in the state. According to Census reports, Pulaski County has an estimated 392,680 residents.
Los Angeles County, California
Not only is Los Angeles County the largest county in California, but it’s also the biggest county – population-wise – in the entire country. Census records show that more than 10 million people call the City of Angels (and its immediate surrounding area) home as of 2018.
County of Denver, Colorado
Fairfield County, Connecticut
With an estimated population of 943,823, Fairfield County has more residents than any other county in Connecticut. Another fun fact about Fairfield County? Four major universities call the area home including Fairfield University, Sacred Heart University, University of Bridgeport, and Western Connecticut State University.
New Castle County, Delaware
The entire state of Delaware only has a population of roughly 967,171 people, so don’t expect to be blown away by the size of the biggest county. The bulk of those residents – 559,335 to be exact– live in New Castle County, making it the largest county in the tiny, mid-Atlantic state.
District of Columbia
Given that the District of Columbia isn’t a state, it doesn’t have any counties. But, it’s worth including in this roundup so you know just how many people live in the political pulse of the US. Per the US Census, the number of DC residents clocks in at roughly 702,455 as of July 2018.
Miami-Dade County, Florida
More than 21 million people live in the Sunshine State and many of them live in Miami-Dade County. Home to the Miami Heat and beautiful Florida beaches, over 2.7 million Floridians reside in Miami, according to data from the US Census.
Fulton County, Georgia
Georgia may be best known for its delectable peaches, but did you know that Fulton County is the largest county in the historical state? Records show that over 1 million residents live within Fulton County limits, more than any other county in the state.
Honolulu County, Hawaii
Honolulu is one of the most well-known cities in Hawaii. But, did you know that Honolulu County is also the largest county in terms of population? Just over 980,000 people call themselves residents of Honolulu County.
Ada County, Idaho
You can certainly find plenty of potatoes in Ada County, Idaho (including this one that’s available to rent on Airbnb), but you can also find lots of people, too. Ada County, Idaho is the state’s most populated county with roughly 469,966 residents as of July 2018.
Cook County, Illinois
Chicago, one of the biggest cities in the US, falls smack dab in Cook County, Illinois. You don’t have to connect many dots to realise that Cook County is the biggest county in Illinois with more than 5.1 million residents.
Marion County, Indiana
Out of the 92 counties in Indiana, Marion County is the winner when it comes to size. In fact, an estimated 954,670 people live in Marion County including residents of Indianapolis, according to the US Census.
Polk County, Iowa
The biggest county in Iowa, also known as the Hawkeye State, is Polk County. As of July 2018, approximately 487,204 people lived in Polk County. The midwest county is home to attractions like Adventureland Park and Blank Park Zoo.
Johnson County, Kansas
Jefferson County, Kentucky
According to population numbers, the largest county in Kentucky is Jefferson County. The region has 770,517 residents as of July 2018 and encompasses the state’s biggest city: Louisville.
East Baton Rouge Parish, Louisiana
In Louisiana, the land is divided by parishes instead of counties. So, what’s the largest parish? It’s the East Baton Rouge Parish, which, of course, includes the city of Baton Rouge. A total of more than 440,000 people live in the East Baton Rouge Parish.
Cumberland County, Maine
Cumberland County, which includes the coastal city of Portland, has 293,557 residents as of July 2018. Why does this matter? Well, that makes it the largest county within Maine.
Montgomery County, Maryland
Located roughly 25 miles from the nation’s capital is Montgomery County, Maryland. The total number of residents exceeds 1 million, making Montgomery County the largest county in the Old Line State.
Middlesex County, Massachusetts
Middlesex County, Massachusetts doesn’t include all of Boston proper, but it does include several outlying neighbourhoods including Waltham, Cambridge, Concord, and Somerville. The county boasts more than 1.6 million residents.
Wayne County, Michigan
It comes as no surprise that Wayne County is the largest county in Michigan. After all, the county includes Detroit – a major hub for the auto industry. As of July 2018, roughly 1,753,893 people live in Wayne County.
Hennepin County, Minnesota
Hinds County, Mississippi
What’s the largest county in Mississippi? Hinds County. The area has an estimated 237,085 residents as of July 2018 and includes Jackson, the capital city of Mississippi.
St. Louis County, Missouri
With almost 1 million residents, St. Louis County takes the No. 1 spot for the largest county in Missouri. The total number of residents in the eastern Missouri county is right around 996,945, according to US Census records.
Yellowstone County, Montana
Billings, Montana is smack dab in the middle of Yellowstone County, the largest county in all of Montana. The total headcount for the county is roughly 160,137. That’s more than any other county in Big Sky Country.
Douglas County, Nebraska
An estimated 566,880 people live in Douglas County, Nebraska, according to US Census records. That means that Douglas County is the largest county Nebraska has to offer.
Clark County, Nevada
The bright lights of Sin City are enough to designate Clark County as the largest county in Nevada. So, just how many people reside here? US Census estimates put the population count at over 2.2 million as of July 2018.
Hillsborough County, New Hampshire
What county in New Hampshire has roughly 415,247 residents? It’s Hillsborough County, of course. The county is also home to Manchester – the state’s largest city.
Bergen County, New Jersey
The bright lights across the Hudson River can’t outshine Bergen County, the largest county in New Jersey. Per Census estimates from July 2018, nearly 936,692 people live in Bergen County, New Jersey. That number makes it the largest county in the Garden State.
Bernalillo County, New Mexico
Kings County, New York
Move over Manhattan, Kings County (aka the Brooklyn Borough) is the latest county in New York State. More than 2.5 million people live in New York’s largest county.
Mecklenburg County, North Carolina
Located in the southwest part of North Carolina is Mecklenburg County. You may not recognise the county by name but you probably recognise Charlotte (the biggest city within county lines). It’s the largest county in the state with 1,093,901 residents as of July 2018.
Cass County, North Dakota
Cass County is the largest county in North Dakota. Of the 760,000-plus residents that live in Roughrider Country, roughly 181,000 of them live in Cass County.
Cuyahoga County, Ohio
With Cleveland as its pulse, Cuyahoga County is the largest county in Ohio. The county sits on Lake Erie and is home to more than 1.2 million people as of July 2018.
Oklahoma County, Oklahoma
Oklahoma County, Oklahoma touts about 792,582 residents – including individuals who live in Oklahoma City. Its vast population makes it the largest county in Oklahoma.
Multnomah County, Oregon
There are a total of 36 counties in Oregon, and of those counties, Multnomah is the largest. The county, which includes the metropolis of Portland, has roughly 811,880 residents.
Philadelphia County, Pennsylvania
Philadelphia has great cheesesteaks, the Liberty Bell, a few major sports teams, but did you know that Philadelphia County is the largest county in the state? With more than 1.5 million estimated residents, it’s worth noting that Philadelphia County takes first place in size.
Providence County, Rhode Island
Rhode Island is a tiny slice of New England. In fact, the state is only made up of five counties. So, what’s the largest one? According to US Census data, Providence County is the winner with roughly 636,084 residents.
Greenville County, South Carolina
Located in the northern part of South Carolina, Greenville County is home to about 514,213 people. The city of Greenville, located within the county, boasts a mild climate with an average annual temperature of 60 degrees Fahrenheit and the largest public school system in the state.
Minnehaha County, South Dakota
Founded in 1862, Minnehaha County is the largest county in South Dakota. According to data from the US Census Bureau, roughly 192,876 people reside within the county. For that reason, it’s the biggest county in the entire state.
Shelby County, Tennessee
Shelby County, Tennessee has a couple of claims to fame. Not only does it encompass Memphis, the home of the Blues, but it is also the largest county in the Volunteer State. More than 935,000 people live in Shelby County, according to the US Census.
Harris County, Texas
Of the 254 counties in Texas, Harris County takes the cake for the largest. The county includes the city of Houston, which helps contribute to its robust population numbers. More than 4.6 million people live in Harris County as of July 2018, according to the most recent Census numbers.
Salt Lake County, Utah
Salt Lake County is known for more than its snow-covered mountain tops and summertime nature hikes – it’s also the largest county in Utah. More than 1.1 million residents called Salt Lake County home as of July 2018.
Chittenden County, Vermont
Chittenden County has the prestigious honour of being home to Ben & Jerry’s, but it’s also noteworthy for another reason. It’s the largest county in Vermont, touting more than roughly 164,000 residents.
Fairfax County, Virginia
If you work in Washington DC, there’s a high chance you probably live in Virginia’s largest county. As of July 2018, Census records show that Fairfax County had more than 1.1 million residents.
King County, Washington
Out in the pacific northwest, King County is the top contender for the largest county in Washington State. The area, which includes Seattle, is home to more than 2.2 million people.
Kanawha County, West Virginia
Home to Charleston, West Virginia’s state capital, is Kanawha County. Recent Census numbers show that just about 180,454 people call the county home, making it the biggest county in West Virginia.
Milwaukee County, Wisconsin
There’s no if, ands, or buts about it – Milwaukee County is the largest county in Wisconsin. More than 948,000 people called Milwaukee County home as of July 2018.
Laramie County, Wyoming
Last, but certainly not least, is Laramie County, Wyoming. It’s the largest county in the Cowboy State. As of July 2018, the resident count was sitting right below the six-figure mark at an estimated 98,976 residents.
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