Více než 83% američanů žije v jedné z 361 metropolitních oblastí. V roce 2005 bylo ve Spojených státech 254 měst s populací větší než 100 tisíc, 9 měst mělo více než 1 milion obyvatel a 4 města (New York, Los Angeles, Chicago a Houston) s populací větší než 2 miliony.
Ve Spojených státech je 50 metropolitních oblastí, které mají počet obyvatel přes 1 milion. Mezi nejrychleji rostoucí aglomerace patří Phoenix.

Pro aglomerace se používá několik různých statistika metod sčítání, např. '''Metropolitan Statistical Area''' (''Metropolitní oblast'') zahrnuje centrální město a na něj navazující předměstí. Naopak '''Combined Statistical Area''' (''Kombinované oblasti'' - CSA) do sebe zahrnuje jak metropolitní oblast, tak mikropolitní oblasti, tzn. že CSA zahrnuje daleko větší oblasti.

== Metropolitní oblasti ==
{| class="wikitable sortable"
|-
! valign=bottom | Pořadí
! valign=bottom | Metropolitní statistická oblast
! valign=bottom | Stát(y)
! valign=bottom | 1.června 2006<br>Odhad populace
|-

In the counties and for some towns over counties, similar areas are defined based on town units, known as New England City and Town Areas (NECTAs).

MSAs are delineated on the basis of a central '''urbanized area'''&mdash;a contiguous area of relatively high population density. The counties containing the core urbanized area are known as the '''central counties''' of the MSA. Additional surrounding counties (known as '''outlying counties''') can be included in the MSA if these counties have strong social and economic ties to the central counties as measured by commuting and employment. Note that some areas within these outlying counties may actually be rural in nature.

MSAs are used for official purposes, but they are not the only estimates of metro area populations available. The appropriate figures for some metro areas are much debated, and in some cases reputable sources provide figures which differ by millions. The most contentious examples include the Detroit, Buffalo, El Paso and San Diego are often substantially larger than their MSA figures.

As of June 2003, there is now an additional classification, that of a “Metropolitan Division.”  The term metropolitan division is used to refer to a county or group of closely-tied contiguous counties that serve as a distinct employment region within a metropolitan statistical area that has a population core of at least 2.5 million.  While a metropolitan division is a subdivision of a larger metropolitan statistical area, it often functions as a distinct social, economic, and cultural area within the larger region.

==Top 25==
The following is a list of the 25 most populated metropolitan statistical areas and metropolitan divisions in the United States, according to the July 1, 2007 U.S. Census Bureau estimates:<ref>http://www.census.gov/population/www/estimates/metro_general/2007/CBSA-EST2007-01.csv</ref>

{| class="wikitable"
|-
! Rank
! Metropolitan Area
! Metropolitan Division
! State(s)
! Population
<!-- #1 NY -->
|-
| align="center" rowspan="5"| 1
| New York–Northern New Jersey–Long Island
| &nbsp; 
| align="center"| NY–NJ–PA
| align=right | '''18,815,988'''
|-
| &nbsp;
| Edison
| align="center"| NJ
| align=right | 2,319,704
|-
| &nbsp;
| Nassau–Suffolk
| align="center"| NY
| align=right | 2,759,762
|-
| &nbsp; 
| Newark–Union
| align="center"| NJ-PA
| align=right | 2,128,679
|-
| &nbsp; 
| New York–White Plains–Wayne
| align="center"| NY-NJ
| align=right | 11,607,843
|-
<!-- #2 Southland -->
|-
| align="center" rowspan="3"|2
| Los Angeles–Long Beach–Santa Ana
| &nbsp;
| align="center" rowspan="3"| CA
| align=right | '''12,875,587'''
|-
| &nbsp; 
| Los Angeles–Long Beach–Glendale
| align=right | 9,878,554
|-
| &nbsp; 
| Santa Ana–Anaheim–Irvine
| align=right | 2,997,033
|-
<!-- #3 Chicago -->
|-
| align="center" rowspan="4"|3
| Chicago–Naperville–Joliet
| &nbsp;
| align="center"| IL–IN–WI
| align=right | '''9,524,673'''
|-
| &nbsp; 
| Naperville–Joliet
| align="center"| IL
| align=right | 7,952,540
|-
| &nbsp; 
| Gary
| align="center"| IN
| align=right | 698,971
|-
| &nbsp; 
| Lake County–Kenosha County
| align="center"| IL–WI
| align=right | 873,162
|-
<!-- #4  -->
|-
| align="center" rowspan="3"|4
| Dallas–Fort Worth–Arlington
| &nbsp;
| align="center" rowspan="3"|TX
| align=right | '''6,145,037'''
|-
| &nbsp;
| Dallas–Plano–Irving
| align=right | 4,111,529
|-
| &nbsp; 
| Fort Worth–Arlington
| align=right | 2,033,508
|-
| align="center" rowspan="4"|5
| Philadelphia–Camden–Wilmington
|
| align="center"| PA–NJ–DE–MD
| align=right | '''5,827,962'''
|-
| &nbsp; 
| Camden
| align="center"| NJ
| align=right | 1,246,339
|-
| &nbsp;
| Philadelphia
| align="center"| PA
| align=right | 3,887,694
|-
| &nbsp; 
| Wilmington
| align="center"| DE–MD–NJ
| align=right | 693,929
|-
| align="center"| 6
| Houston–Sugar Land–Baytown
| &nbsp;
| align="center" | TX
| align=right | '''5,628,101'''
|-
| align="center" rowspan="4"| 7
| Miami–Fort Lauderdale–Pompano Beach
| &nbsp;
| align="center" rowspan="4"|FL
| align=right | '''5,413,212'''
|-
| &nbsp; 
| Fort Lauderdale–Pompano Beach–Deerfield Beach
| align=right | 1,759,591
|- 
| &nbsp;
| Miami–Miami Beach–Kendall
| align=right | 2,387,170
|-
| &nbsp; 
| West Palm Beach–Boca Raton–Boynton Beach
| align=right | 1,266,451
|-
| align="center" rowspan="3"|8
| Washington–Arlington–Alexandria
| &nbsp;
| align="center"| DC–VA–MD–WV
| align=right | '''5,306,565'''
|-
| &nbsp; 
| Bethesda-Gaithersburg–Frederick
| align="center"| MD
| align=right | 1,155,518
|-
| &nbsp; 
| Washington–Arlington–Alexandria
| align="center"| DC–MD–VA–WV
| align=right | 4,151,047
|-
| align="center"| 9
| Atlanta–Sandy Springs–Marietta
|&nbsp;
| align="center"| GA
| align=right | '''5,278,904'''
|-
|  align="center" rowspan="5"| 10
| Boston–Cambridge–Quincy
| &nbsp;
| align="center"| MA–NH
| align=right | '''4,482,857'''
|-
| &nbsp; 
| Boston–Quincy
| align="center" rowspan="3" |MA
| align=right | 1,858,216
|-
| &nbsp; 
| Cambridge–Newton–Framingham
| align=right | 1,473,416
|-
| &nbsp; 
| Peabody
| align=right | 733,101
|-
| &nbsp;
| Rockingham County–Strafford County
| align="center"| NH
| align=right | 418,124
|-
|  align="center" rowspan="3"| 11
| Detroit–Warren–Livonia
| &nbsp;
| align="center" rowspan="3"|MI
| align=right | '''4,467,592'''
|-
| &nbsp;  
| Detroit–Livonia–Dearborn
| align=right | 1,985,101
|-
| &nbsp; 
| Warren–Troy–Farmington Hills
| align=right | 2,482,491
|-
|  align="center" rowspan="3"| 12
| San Francisco–Oakland–Fremont
| &nbsp;
| align="center" rowspan="3"|CA
| align=right | '''4,203,898'''
|-
| &nbsp;
| Oakland–Fremont–Hayward
| align=right | 2,483,842
|-
| &nbsp;
| San Francisco–San Mateo–Redwood City
| align=right | 1,720,056
|-
|  align="center"| 13
| Phoenix–Mesa–Scottsdale
| &nbsp;
| align="center"| AZ
| align=right | '''4,179,427'''
|-
|align="center" rowspan="3"| 14
| Seattle–Tacoma–Bellevue
| &nbsp;
| align="center" rowspan="3"|WA
| align=right| '''4,109,347'''
|-
| &nbsp;
| Seattle–Bellevue–Everett
| align=right | 2,536,182
|-
| &nbsp;
| Tacoma
| align=right | 773,165

|-
|  align="center"| 15
| Riverside–San Bernardino–Ontario
| &nbsp;
| align="center"| CA
| align=right | '''4,081,371'''
|-
| align="center"| 16
| Minneapolis–St. Paul–Bloomington
| &nbsp;
| align="center"| MN&ndash;WI
| align=right | '''3,208,212'''
|-
| align="center"| 17
| San Diego–Carlsbad–San Marcos<ref>This population is only for the United States side. The area is also included together with the city of Tijuana in Mexico in the bi-national conurbation known as the San Diego-Tijuana Metropolitan Area which together have a population of 4,945,410.</ref>
| &nbsp;
| align="center"| CA
| align=right | '''2,974,859'''
|-
| align="center"| 18
| St. Louis
| &nbsp;
| align="center"| MO–IL
| align=right | '''2,803,707'''
|-
| align="center"| 19
| Tampa–St. Petersburg–Clearwater
| &nbsp;
| align="center"| FL
| align=right | '''2,723,949'''
|-
| align="center"| 20
| Baltimore–Towson
| &nbsp;
| align="center"| MD
| align=right | '''2,668,056'''
|-
| align="center"| 21
| Denver–Aurora
| &nbsp;
| align="center"| CO
| align=right | '''2,464,866'''
|-
| align="center"| 22
| Pittsburgh
| &nbsp;
| align="center"| PA–WV
| align=right | '''2,355,712'''
|-
| align="center"| 23
| Portland–Vancouver–Beaverton
| &nbsp;
| align="center"| OR–WA
| align=right | '''2,175,113'''
|-
| align="center"| 24
| Cincinnati–Middletown
| &nbsp;
| align="center"| OH-KY-IN
| align=right | '''2,133,678'''
|-
| align="center"| 25
| Cleveland–Elyria–Mentor
| &nbsp;
| align="center"| OH
| align=right | '''2,096,471'''
|}