In 48 of the 50 states of the United States, the county is used for the level of local government immediately below the state itself. Louisiana uses parishes, and Alaska uses boroughs. In several states in New England, some or all counties within states have no governments of their own; the counties continue to exist as legal entities, however, and are used by states for some administrative functions and by the United States Census bureau for statistical analysis. There are 3,242 counties and county equivalent administrative units in total, including the District of Columbia and 100 county-equivalents in the U.S. territories. There are 41 independent cities in the United States. In Virginia, any municipality that is incorporated as a city legally becomes independent of any county. Where indicated, the statistics below do not include Virginia's 38independent cities. In Alaska, most of the land area of the state has no county-level government. Those parts of the state are divided by the United States Census Bureau into census areas, which are not the same as boroughs. The state's largest statistical division by area is the Yukon–Koyukuk Census Area, which is larger than any of the state's boroughs. Although Anchorage is called a municipality, it is considered a consolidated city and borough. There are 100 county-equivalents in the territories of the United States: they are the 3 districts and 2 atolls of American Samoa, all of Guam, the 4 municipalities in the Northern Mariana Islands, the 78 municipalities of Puerto Rico, the 3 main islands of the U.S. Virgin Islands, and the 9 islands in the U.S. Minor Outlying Islands. All of these territorial county-equivalents are defined by the U.S. Census Bureau.
Count
This is the number of counties and county-equivalents for each state, the District of Columbia, the 5 inhabited territories of the United States, and the U.S. Minor Outlying Islands. Lists of counties and county equivalents by number per political division:
Alaska has no counties. The following areas in Alaska are counted as county-equivalents: the 19 organized boroughs and, in its Unorganized Borough, of 10 designated census areas.
8 of the 14 counties in Massachusetts were disincorporated in the 1990s and early 2000s; local government in these areas consists of cities and towns. One of the remaining 6 counties is a consolidated town-county.
14
Vermont
10
New Hampshire
9
U.S. Minor Outlying Islands
The U.S. Minor Outlying Islands does not have counties. The 9 islands in the U.S. Minor Outlying Islands are counted as county-equivalents by the U.S. Census Bureau.
County government was abolished in Connecticut in 1960; local government consists of cities, towns, and boroughs.
5
American Samoa
The 3 districts and 2 unorganized atolls of American Samoa are counted as county-equivalents by the U.S. Census Bureau. American Samoa locally has 14 “counties”, but these “counties” are not counted as counties by the U.S. Census Bureau.
Counties in Rhode Island have no governmental functions; local government is provided by eight cities and thirty-one towns
4
Northern Mariana Islands
The Northern Mariana Islands has no counties. The 4 municipalities of the Northern Mariana Islands are counted as county-equivalents by the U.S. Census Bureau.
The U.S. Virgin Islands has no counties. The 3 main islands of the U.S. Virgin Islands are counted as county-equivalents by the U.S. Census Bureau.
1
District of Columbia
The District of Columbia has no counties; the District of Columbia is considered both a state-equivalent and a county equivalent for statistical purposes
1
Guam
Guam has no counties; Guam is considered both a state-equivalent and a county-equivalent for statistical purposes by the U.S. Census Bureau.
Total : 3,142
Total : 3,242
Average number of counties per state : 62.82
Average number of counties per state : 56.87
Population
Nationwide population extremes
These rankings include county equivalents.
The following is a list of the least populous counties and county-equivalents in all U.S. territory. Note that the only entity on this list with a permanent human population is Swains Island, American Samoa. The first 8 counties are uninhabited, while the 10th on the list has a small non-permanent human population whose maximum capacity is 20 people.
The largest counties and county-equivalents are organized boroughs and the census areas of Alaska with the top two being Yukon–Koyukuk Census Area and North Slope Borough. The smallest counties and county equivalents are the independent cities of Virginia with the extreme being Falls Church. If the U.S. territories are included, the smallest county-equivalent is Kingman Reef, with a land area of 0.01 square miles. The following two tables exclude county-equivalents:
Smallest, largest and average area per state and territory
The following is a list of counties and county-equivalents showing the average size of each state/territory’s counties, the smallest county in each state/territory, and the largest county in each state/territory. States/territories on the list are arranged by the average land area of their counties. Though not on the list, the North Slope Borough is the largest independently incorporated county equivalent. The Unorganized Borough is substantially larger, but is an extension of the State of Alaska government and not independently incorporated. Also note that the smallest land area with county-level governance in the U.S. is Falls Church, Virginia, but it is an independent city and not a county or part of one. Kingman Reef is the smallest county-equivalent in all U.S. territory. Kalawao County, Hawaii is the smallest true county by land area.
Data presented below is based on U.S. Census department data from 2010. Calculations are made by dividing the population by the land area. All county equivalents are included. This list includes the 50 most densely-populated counties and county-equivalents in the 50 states and District of Columbia, plus the 9 highest-density municipalities of Puerto Rico. Puerto Rico is the only U.S. territory with population densities high enough to be on this list. Note that many of these high-density counties are coterminous with large cities or are independent cities in Virginia which are considered county-equivalents.
This list was generated by dividing the population by the land area. All county equivalents are included. The list is dominated by just a few states: Alaska, Montana, and Texas together comprise about two-thirds of the entries. The Unorganized Borough is not included here as a unit, but its census areas are. If the census areas were removed from the list, the Unorganized Borough would rank fourteenth with a density of. The 8 uninhabited county-equivalents in the U.S. territories are listed at the top of the table — these are technically the least-densely populated counties/county-equivalents in the United States, but since they have no people, they are listed unranked.
Data presented below is based on U.S. Census Bureau data from 2010. Calculations are made by dividing the population by the land area. All county equivalents are included. Excluding the census areas of Alaska, Lake and Peninsula Borough is the least densely populated county equivalent with. The District of Columbia and Guam each only have one county-equivalent, so their most/least densely-populated county is the same.
Texas
Georgia
Virginia
Kentucky
Missouri
Kansas
Illinois
North Carolina
Iowa
Tennessee
Nebraska
Indiana
Ohio
Minnesota
Michigan
Mississippi
Puerto Rico
Oklahoma
Arkansas
Wisconsin
Alabama
Florida
Pennsylvania
South Dakota
Colorado
Louisiana
New York
California
Montana
West Virginia
North Dakota
South Carolina
Idaho
Washington
Oregon
New Mexico
Alaska
Utah
Maryland
Wyoming
New Jersey
Nevada
Maine
Arizona
Massachusetts
Vermont
New Hampshire
U.S. Minor Outlying Islands
Connecticut
American Samoa
Hawaii
Rhode Island
Northern Mariana Islands
Delaware
Virgin Islands 
District of Columbia
Guam